don't get your panties in a bunch

slang Don't become overly upset or emotional over something, especially that which is trivial, unimportant, or easily resolved. Primarily heard in US. Ah, don't get your panties in a bunch. I'll have the car back by tomorrow morning! All right, all right—don't get your panties in a bunch. I'm sure we'll find a solution to this problem. Would you calm down? This really isn't a big deal, so don't get your panties in a bunch.