: 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, it gained broader colloquial popularity by the 1970s as a metaphorical way to advise patience or emotional control. When to Use It 1. Cool Your Jets
The phrase emerged in the during the mid-20th century, a period deeply influenced by rapid developments in aviation and the "Space Age". : To advise caution when someone is acting