Short answer: Many idioms that sound rude are actually friendly. "Break a leg" wishes a performer good luck. "Knock yourself out" means "go ahead, help yourself." "Shut up!" and "Get out of here!" can mean "I don't believe it!" rather than "be quiet" or "leave." "Pull my leg" means to tease. The words sound violent or insulting, but the meaning is kind or playful. What decides whether they land well is tone, setting and how well you know the listener, so each entry below gives the register and region.
Why these idioms trip up learners
A learner meets an idiom one word at a time. "Break," "leg," "knock," "out," "shut" and "kick" are all words with harsh literal meanings, so the first reaction is alarm. Fluent speakers usually do not hear the literal meaning at all. They hear the idiom as a single unit, the way you hear "hello" without thinking about what its parts once meant.
There is a second trap. Several of these phrases have two senses, one friendly and one genuinely rude, and the only difference is tone of voice. "Shut up!" said with a wide smile to a friend who just got good news is praise. "Shut up" said flatly in an argument is an insult. A dictionary label will tell you which sense is which, but in real speech you have to listen for the tone.
The register, region and "safe at work" notes below are our own guidance for learners, not dictionary labels. Meanings and origins come from the named references, which we read on September 28, 2026.
Quick reference table
| Idiom | What it really means | Register | Region | Safe at work? |
|---|---|---|---|---|
| Break a leg! | Good luck (to a performer) | Casual, warm | US and UK | Yes, before a presentation |
| Knock yourself out | Go ahead, help yourself | Casual | US and UK | Among friendly colleagues |
| Shut up! (surprised) | I don't believe it! | Very casual | Understood widely | No |
| Get out of here! (surprised) | No way, really? | Very casual | Understood widely | No |
| Pull someone's leg | Tease them | Casual | US and UK | Yes |
| Beat around the bush | Avoid the main point | Neutral | US and UK | Yes |
| A pain in the neck | Annoying | Casual | US and UK | About things, not people |
| Kick the bucket | Die | Casual, jokey | US and UK | No |
| Keep your shirt on | Calm down | Casual | US and UK | No |
Idioms that sound rude but are friendly
Break a leg
"Break a leg" is said to actors and other performers before they go on stage, and it means good luck. It is warm, not cruel. The Phrase Finder's entry on "break a leg" says plainly that why the wish took this form "has never been settled." Its leading theory is superstition: wishing a performer good luck was thought to bring bad luck, so people wished the opposite. It lists other theories, including a performer bowing after applause, but does not endorse them. The earliest example it gives is from The Charleston Gazette in May 1948.
Register: casual and warm. Region: both American and British English. Outside the theater, people now say it before a speech, a job interview or a big presentation.
Knock yourself out
This sounds like advice to hit yourself on the head. It actually means "go ahead, do as you like, enjoy yourself." Wiktionary labels it idiomatic and informal, and gives the classic use: someone asks if they can have some cookies, and the answer is "Sure, knock yourself out."
One caution: Wiktionary also records a sarcastic use, showing a lack of interest. "I'm going to the store." "Knock yourself out." That version means "fine, but count me out." Tone tells you which is meant.
Register: casual. Region: both.
Shut up! (as surprise)
"Shut up" has two very different meanings. Wiktionary's entry for "shut up" labels the "stop talking" sense highly impolite and suggests "be quiet" as the neutral alternative. But it also lists a colloquial sense meaning "I don't believe it!" or "no way!", with the example of someone reacting to a friend's news about getting into Yale, and notes that this sense is not usually taken as offensive.
Register: very casual, friends only. Region: understood widely, but because the rude sense sits right next to it, treat it as risky with anyone who might miss your tone. "No way!" does the same job safely.
Get out of here! (as surprise)
The same pattern. Literally, it orders someone to leave. As an exclamation of disbelief, Wiktionary labels it idiomatic and informal: "Did she really say that? Get out of here!" It lists "get out of town" as a synonym in this sense.
Register: very casual. Avoid it in writing and with people you do not know well, where the literal order is the likelier reading.
Pull someone's leg
"Are you pulling my leg?" means "Are you teasing me?" Nobody is touching anyone's leg. Wiktionary defines it as to tease someone or lead them on, and says the expression originated in Scotland. It adds that one proposed origin, tripping someone to make them look foolish, is only a theory.
Register: casual and friendly. Region: both. This one is safe in almost any setting, including light conversation at work.
Beat around the bush
This sounds aggressive, and some learners also suspect a hidden rude meaning. There is none. It means to avoid the main point, often on purpose. Wiktionary says the modern form replaced the older "beat about the bush," and its earliest quotation for the "around" form is from Horatio Alger's Rufus and Rose (1870): "I don't like beating around the bush."
Register: neutral, fine in business. "Let's not beat around the bush" is a polite way to get to a hard topic. Region: both.
Idioms that sound harsh but are mild
A pain in the neck
"This printer is a pain in the neck" means it is annoying. Wiktionary labels the phrase idiomatic slang, dates it to the 1920s and quotes P.G. Wodehouse in 1923: "Wouldn't that give you a pain in the neck!" It is mild. Be careful with its cousins, though: Wiktionary lists "pain in the ass" and "pain in the butt" as synonyms, and both are much cruder.
Register: casual. Calling a thing a pain in the neck is fine at work. Calling a person one, to their face, is rude.
Kick the bucket
To "kick the bucket" means to die. It is not offensive, but it is jokey, so it is wrong for a sympathy card or a funeral. Use it about fictional characters or your own old car, not about someone the listener has lost. Our page on the kick the bucket origin explains why the "bucket" in the phrase was a beam, not a pail.
Register: casual, humorous. Region: both.
Keep your shirt on
"Keep your shirt on" means calm down, be patient. Wiktionary labels it informal and usually used as an order. The friendly intent is real, but any phrase that tells someone to calm down can sound bossy.
Register: casual; use it with friends and family, not with a customer or a manager.
When the rude-sounding version really is rude
The friendly idioms above have neighbors that are not friendly at all. These are the ones to keep out of polite settings:
- "Shut up" meaning "stop talking." Wiktionary calls it rude, forceful and impolite.
- "Get out of here" as an order. Said flatly, it tells someone to leave.
- "Pain in the ass." The cruder synonym of "pain in the neck."
- Sarcastic "knock yourself out." Friendly words used to dismiss someone.
The difference is almost never the words. It is the tone, the relationship and the setting. If you cannot control all three, choose the plain option: "No way!", "Go ahead," "Good luck," "Please calm down."
Learners who mix up two similar idioms face a related problem, covered in our guide to commonly misused idioms. And if you want to know why an idiom's literal words and its meaning drift so far apart, our explainer on where idioms come from is a good next read.
Frequently asked questions
Is "break a leg" rude?
No. It means good luck and is said warmly to performers, and now to anyone facing a big moment. The Phrase Finder says its origin has never been settled; the leading theory is a superstition against saying "good luck" directly.
What does "knock yourself out" mean?
It means "go ahead, help yourself" or "enjoy yourself." Wiktionary labels it informal. It can also be used sarcastically to show you are not interested, so listen for the tone.
Is "shut up" always rude?
No. When it means "stop talking," Wiktionary labels it highly impolite. When it expresses surprise, as in "Shut up, really? That's awesome!", Wiktionary notes it is not usually taken as offensive. Keep that use for friends.
Can I say "pull my leg" at work?
Yes. "Are you pulling my leg?" simply means "Are you teasing me?" and is friendly in almost any setting.
