keep (one's) shirt on

keep (one's) shirt on

To remain calm and wait for something. Typically used as an imperative in the phrase "keep your shirt on." Keep your shirt on, dude, the pizza will be here soon enough. It would have gone smoothly if Larry had been able to keep his shirt on instead of trying to get in early.
See also: keep, on, shirt
Farlex Dictionary of Idioms.

keep one's shirt on

 and keep one's pants on
Fig. to be patient. Wait a minute! Keep your shirt on! Keep your pants on! I'll be with you in a minute.
See also: keep, on, shirt

Keep your shirt on!

 and Keep your pants on!
Inf. Just wait a minute! I'll be right with you. Keep your shirt on! Keep your pants on! You're next.
See also: keep, shirt
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

keep one's shirt on

Stay calm, be patient; not give way to temper or excitement. For example, Keep your shirt on, Bob, they'll be here in time for the wedding. [Colloquial; mid-1800s]
See also: keep, on, shirt
The American Heritage® Dictionary of Idioms by Christine Ammer.

keep your shirt on

BRITISH, AMERICAN, INFORMAL or

keep your pants on

mainly AMERICAN, INFORMAL
If someone tells you to keep your shirt on or keep your pants on, they are telling you to calm down and not be angry or impatient. The doorbell rang. Helen told the caller to keep his shirt on — angry because she felt the ringing had been excessive. Note: This expression is often used to suggest that a person's anger or impatience is not reasonable. Compare with keep your hair on.
See also: keep, on, shirt
Collins COBUILD Idioms Dictionary, 3rd ed.

keep your shirt on

don't lose your temper; stay calm. informal
See also: keep, on, shirt
Farlex Partner Idioms Dictionary

Keep your shirt on!

and Keep your pants on!
exclam. Just wait a minute!; Don’t be in a rush. (Possibly said as if to avoid a fight, for which one removes one’s shirt. That is, Let’s not rush into a big argument or fight; wait a minute. The expressions are old and in very wide use, too wide to suggest a reference to sexual urgency.) I’ll be right with you. Keep your shirt on! We’ll be there in a minute! Keep your pants on!
See also: keep, shirt
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions

keep (one's) shirt on

Slang
To remain calm or patient: The plane doesn't land for another hour, so keep your shirt on.
See also: keep, on, shirt
American Heritage® Dictionary of the English Language, Fifth Edition.

keep your shirt on

Remain calm and patient; don’t lose your temper. Dating from the nineteenth century, this American expression refers to the practice of a man removing his shirt before a fight, lest it get torn, and at first literally meant not to rush into a fight. “Tell E. Stanton to keep his undergarmints on,” wrote Artemus Ward (In Washington, 1863). Later it came to mean being patient as well.
See also: keep, on, shirt
The Dictionary of Clichés by Christine Ammer
See also:
  • keep it that way
  • keep in
  • keep in some place
  • earn its keep
  • keep away
  • keep away (from someone or something)
  • bear/keep somebody/something in mind
  • keep (something) under wraps
  • keep (one's) eye(s) out (for something or someone)
  • keep eye out