cool your jets!

cool (one's) jets

1. To calm oneself down; to become less agitated. I was really angry, so I had to just take a second and cool my jets before I did anything rash. Cool your jets back there, we'll be home in a few minutes. Would you cool your jets? The staff members you're yelling at didn't do anything wrong.

2. To stifle or control one's eagerness, enthusiasm, or hastiness. The young senator has massive support in his home state, but he'd better cool his jets if he thinks the rest of the country will consider him presidential material. I know you want to get this project over and done with, but cool your jets and do the work carefully. Cool your jets, all right? If you're done all that data entry already, you must have made mistakes.

cool your jets!

Calm down! This caution began with air force pilots reducing their jet planes' air speed and, by so doing, reducing strain on the engine caused by excess heat. Among similar “relax!” phrases are “hold your horses!” “chill out!” “keep your pants on!” and “don't get your bowels in an uproar!”