12 Idioms for Best Friends You Should Know

Idioms for best friends add color and warmth to how we talk about the people closest to us. Whether you’re writing a toast, captioning a photo, or just want to express appreciation, these phrases capture the unique bond of true friendship. This post covers 12 timeless idioms, what they mean, and how to use them naturally in everyday conversation.

Simply put, these 12 idioms for best friends range from playful (“partners in crime”) to heartfelt (“through thick and thin”). Each one captures a different side of friendship, so you can pick the perfect phrase for any occasion.

Key Takeaways

• Idioms for best friends fall into categories: loyalty, similarity, mischief, and emotional support.
• Knowing the origin of each idiom helps you use it in the right context.
• Most of these phrases work in casual speech, social media captions, and even heartfelt letters.
• Some idioms like “ride or die” feel modern, while others like “bosom buddies” sound old-fashioned but charming.
• Using these idioms correctly makes your English sound more natural and expressive.

1. Two Peas in a Pod – For Friends Who Are Inseparable

“Two peas in a pod” describes friends who are practically inseparable. They do everything together, finish each other’s sentences, and often share similar tastes, habits, and even mannerisms.

This idiom works perfectly when you want to highlight how closely two people match. You might hear it from parents describing childhood friends or from coworkers talking about a duo that always collaborates.

• Meaning: extremely similar or always together
• Tone: warm, affectionate, slightly playful
• Best used for: childhood friends, siblings who are close, work partners
• Example: “Maya and Priya are two peas in a pod – they even order the same coffee.”
• Origin: dates back to the 16th century, comparing friendships to peas naturally growing side by side in a pod

This idiom is one of the most recognisable idioms for best friends in English. It’s safe for any audience and carries a purely positive, wholesome meaning.

Best for: describing friends who share identical routines, interests, or personalities.

2. Thick as Thieves – For Friends Who Share Everything

“Thick as thieves” refers to friends who are extremely close, often sharing secrets that no one else knows. The phrase originally had a negative connotation since thieves needed absolute trust, but today it simply means deep, unbreakable closeness.

Use this when you want to emphasise trust and confidentiality. It’s a step beyond “good friends” – these are people who know your darkest secrets and would never betray you.

Aspect	Detail
Meaning	Very close, sharing secrets
Tone	Casual, slightly mischievous
Example	“Those two are thick as thieves – they tell each other everything.”
Origin	From 16th-century England, referencing how thieves trusted each other completely

Because the phrase mentions “thieves,” some people use it playfully. It’s perfect for describing friends who share gossip, secrets, or inside jokes that nobody else understands.

Best for: close-knit friend groups, siblings who keep secrets, or colleagues with strong alliances.

3. Partners in Crime – For Friends Who Cause (Good) Trouble Together

“Partners in crime” describes friends who team up for adventures, pranks, or slightly rebellious activities. Despite the word “crime,” the phrase is almost always used affectionately and humorously.

This is one of the most popular modern idioms for best friends, especially on social media. You’ll see it in Instagram captions, group chat names, and birthday posts.

• Meaning: friends who do things together, often mischievous or adventurous
• Tone: playful, fun, energetic
• Common usage: “My partner in crime and I are off on another adventure.”
• Variations: “partner in crime” can also refer to a romantic partner
• Similar idioms: “accomplice,” “co-conspirator” (used jokingly)

Tip: Use “partners in crime” when you want a lighthearted tone. Avoid it in formal writing or professional contexts where the word “crime” might be taken literally.

The phrase gained popularity in the 20th century and became a staple of buddy movies and sitcoms. It works well for friends who plan spontaneous road trips, try new restaurants, or tackle ambitious DIY projects together.

Best for: adventurous friends, college roommates, or anyone who shares your sense of mischief.

4. Through Thick and Thin – For Loyal Friends Who Stay

“Through thick and thin” means staying loyal to someone during both good times and bad. The “thick” refers to dense, difficult situations, while “thin” refers to easier, smoother periods. Together, they cover the full range of life’s ups and downs.

This idiom carries real emotional weight. Use it in speeches, letters, or serious conversations where you want to acknowledge someone’s steadfast support.

1. Say it at a wedding toast: “She’s been with me through thick and thin.”
2. Write it in a thank-you card after a difficult period.
3. Use it to describe a friendship that has survived moves, job changes, or relationship breakups.
4. Pair it with specific examples: “Through thick and thin – from my first job loss to my biggest promotion.”

According to the Oxford English Dictionary, this phrase dates back to the 17th century and originally described travelling through dense forests and open fields. Over time, it evolved to mean enduring all of life’s challenges together.

Best for: lifelong friends, family members who act as friends, or anyone who has supported you through hardship.

5. Ride or Die – For Modern, Unconditional Loyalty

“Ride or die” is a contemporary idiom that means someone will stick with you no matter what. It comes from hip-hop culture and biker slang, where “ride” means to go on a journey together and “die” represents ultimate commitment.

This phrase has exploded in popularity over the past decade. It’s casual, bold, and carries a sense of adventure that older idioms lack.

• Meaning: loyal to the end, no matter the circumstances
• Tone: modern, edgy, youthful
• Example: “She’s my ride or die – we’ve been through everything together.”
• Usage context: social media bios, group chats, casual conversation
• Related terms: “ride or die chick,” “ride or die homie”

Important: “Ride or die” can also describe a risky situation or a committed romantic partner. Context matters, so pay attention to how it’s used in conversation.

Unlike some older idioms, “ride or die” feels fresh and energetic. It’s perfect for describing friends who would drop everything to help you at 2 AM or join you on a last-minute trip across the country.

Best for: close friends in your age group, adventure buddies, or anyone who embodies unconditional support.

6. A Shoulder to Cry On – For Friends Who Offer Comfort

“A shoulder to cry on” describes a friend who provides emotional support during tough times. It’s a tender, comforting idiom that highlights the nurturing side of friendship.

This phrase is ideal for expressing gratitude toward a friend who has helped you through grief, heartbreak, or stressful periods. It emphasises emotional availability rather than practical help.

Situation	How to Use the Idiom
After a breakup	“I don’t know what I’d do without you – you’re always a shoulder to cry on.”
During grief	“She was a shoulder to cry on at the funeral.”
After a bad day	“Thanks for being a shoulder to cry on after my presentation flopped.”

Research from Harvard Medical School shows that strong social support reduces stress hormones and improves mental health outcomes. Using phrases like this one helps you acknowledge the people who provide that crucial support.

Best for: expressing gratitude, writing sympathy notes, or describing emotionally supportive friendships.

7. Birds of a Feather – For Friends Who Share Similar Traits

“Birds of a feather” comes from the longer saying “birds of a feather flock together.” It means people with similar interests, backgrounds, or personalities naturally gravitate toward each other.

This idiom works in two ways. You can use it positively to celebrate shared interests, or slightly critically to point out that someone surrounds themselves with like-minded people.

• Meaning: people who are similar tend to become friends
• Tone: neutral to positive, observational
• Example: “Birds of a feather – you two both love hiking and indie films.”
• Origin: appears in William Shakespeare’s “Timon of Athens” (1606)
• Modern usage: often shortened to just “birds of a feather” without the second half

Psychologists call this “homophily” – the tendency for people to bond with those who share their values and interests. It’s a natural human behaviour that this idiom captures perfectly.

Best for: describing friend groups with obvious shared traits, or gently teasing someone about their predictable friend choices.

8. Cut From the Same Cloth – For Friends Who Think Alike

“Cut from the same cloth” compares people to fabric cut from the same bolt, meaning they share core qualities or values. It’s similar to “birds of a feather” but emphasises deeper character traits rather than surface-level interests.

This idiom is slightly more formal than others on this list. It works well in speeches, professional settings, or when you want to sound thoughtful about a friendship.

1. Use it to describe siblings who share the same work ethic.
2. Use it for friends who approach problems the same way.
3. Use it when two people have similar moral compasses.
4. Use it to highlight shared values in a professional partnership.

Warning: Don’t confuse this with “cut from the same cloth” meaning identical. It means similar in character, not the same in every way.

The textile metaphor makes this idiom vivid and memorable. It suggests that two people share the same fundamental material, just like garments made from the same fabric roll.

Best for: professional partnerships, family friendships, or describing friends who share your core values.

9. Bosom Buddies – For Old-Fashioned, Close Friends

“Bosom buddies” is a charming, slightly old-fashioned way to describe very close friends. The word “bosom” refers to the chest area, symbolising emotional closeness and intimacy.

This phrase gained popularity in the mid-20th century and became widely known through the 1980s TV sitcom “Bosom Buddies” starring Tom Hanks. Today, it carries a nostalgic, affectionate tone.

• Meaning: very close, intimate friends
• Tone: nostalgic, warm, slightly humorous
• Example: “We’ve been bosom buddies since kindergarten.”
• Similar phrases: “close as can be,” “best of friends”
• Usage note: works best when you want a playful, vintage feel

While it may sound dated to younger generations, many people still love this idiom for its warmth and charm. It’s perfect for describing childhood friends or long-term friendships that have stood the test of time.

Best for: nostalgic contexts, writing about childhood friends, or adding a touch of vintage charm to your language.

10. Friends in High Places – For Friends With Influence

“Friends in high places” refers to having connections with influential or powerful people. While not exclusively about best friends, it’s often used to describe a network that includes people who can open doors for you.

This idiom can be used literally or figuratively. Literally, it means knowing executives, politicians, or celebrities. Figuratively, it means having allies in positions that benefit you.

Context	Example
Job hunting	“She got the interview because she has friends in high places.”
Getting reservations	“He called in a favour – friends in high places, you know.”
Legal trouble	“The case was settled quickly thanks to friends in high places.”

LinkedIn’s 2023 Workplace Relationships Report found that 85% of professionals say networking helped them advance their careers. This idiom captures that reality in a memorable phrase.

Best for: professional contexts, discussing networks, or slightly envious observations about someone’s connections.

11. The Apple of My Eye – For a Cherished Friend

“The apple of my eye” describes someone who is deeply cherished and admired. While it’s often used romantically, it works beautifully for best friends too, especially when you want to express how much they mean to you.

The phrase dates back to Old English, where “apple” referred to the pupil of the eye. Since the pupil was considered essential for vision, calling someone the “apple of your eye” meant they were essential to your life.

• Meaning: someone you cherish above others
• Tone: tender, affectionate, slightly formal
• Example: “She’s the apple of my eye – I’d do anything for her.”
• Historical usage: appeared in Shakespeare’s “A Midsummer Night’s Dream”
• Modern usage: more common in romantic contexts, but works for close friendships

Tip: Reserve this one for your very closest friend. It’s intense and should be used sparingly to maintain its impact.

This idiom is one of the most poetic ways to describe a best friend. It elevates the relationship beyond casual friendship and signals deep emotional investment.

Best for: heartfelt letters, anniversary messages, or moments when you want to express profound appreciation.

12. A Friend in Need Is a Friend Indeed – For Friends Who Show Up

“A friend in need is a friend indeed” is a proverb that means a true friend is someone who helps you when you’re in trouble. The word “need” here refers to times of difficulty, not to someone who is needy.

This is perhaps the most famous friendship proverb in English. It’s often quoted in speeches, greeting cards, and advice columns because it captures the essence of true friendship in a single sentence.

1. Meaning: real friends reveal themselves during hard times
2. Tone: wise, reflective, sincere
3. Example: “When I was sick, she brought me soup every day. A friend in need is a friend indeed.”
4. Origin: traced back to ancient Latin proverb “amicus certus in re incerta cernitur”
5. Modern usage: often shortened to “a friend in need” in casual conversation

Research from the American Psychological Association shows that people with strong social support networks recover faster from illness and report higher life satisfaction. This proverb captures that truth in a memorable, quotable form.

Best for: thank-you notes, eulogies, wedding speeches, or any moment when you want to acknowledge a friend’s loyalty during tough times.

Frequently Asked Questions

What is the most common idiom for best friends?

“Two peas in a pod” is arguably the most widely used and recognised idiom for close friends. It’s simple, universally understood, and carries a positive, wholesome meaning that works across age groups and cultures.

Can I use idioms for best friends in professional settings?

Some idioms like “cut from the same cloth” and “friends in high places” work well professionally. Others like “partners in crime” or “ride or die” are too casual for formal business contexts. Match the idiom to your audience and setting.

What is the difference between “birds of a feather” and “two peas in a pod”?

“Birds of a feather” emphasises shared traits or interests that attract people to each other. “Two peas in a pod” emphasises inseparability and constant togetherness. You can be similar but not inseparable, or inseparable but different in many ways.

Are these idioms used in American and British English equally?

Most of these idioms are understood in both American and British English. However, “bosom buddies” and “thick as thieves” are more common in British English, while “ride or die” originated in American hip-hop culture and is more prevalent in the US.

How can I remember and use these idioms naturally?

Start by choosing two or three that resonate with you and practice using them in conversation. Write them in birthday cards, text messages, or social media captions. Over time, they’ll become part of your natural vocabulary.

Final Thoughts

These 12 idioms for best friends give you a rich vocabulary to express the many dimensions of friendship – from playful mischief to unwavering loyalty. Pick the ones that match your style, and don’t be afraid to mix them. The right phrase at the right moment can say more than a hundred ordinary sentences.