Your Jets — 1. Cool

: While it started in futuristic science fiction, it gained broader colloquial popularity by the 1970s as a metaphorical way to advise patience or emotional control. When to Use It

: One of its earliest recorded uses is in the 1952 novel Stand by for Mars! from the Tom Corbett, Space Cadet series, where a character is told, "Cool your jets, space creep!". 1. Cool Your Jets

: To advise caution when someone is acting impulsively out of enthusiasm (e.g., "Cool your jets, Sarah. Make sure you have the job offer in writing first."). : While it started in futuristic science fiction,

If "cool your jets" feels too informal or dated, you might use: : To advise caution when someone is acting

The phrase emerged in the during the mid-20th century, a period deeply influenced by rapid developments in aviation and the "Space Age".

: To stop someone from getting overly worked up or angry (e.g., "Cool your jets! It's not worth fighting over.").

or Take a chill pill : Modern, very informal ways to say the same thing.