stay frosty

verb2

1. •
   (slang) To be alert and ready for action, without letting one's fear or other emotions get in the way.

   • 1986, 'Corporal Hicks', Aliens (movie): We're all in strung out shape, but stay frosty, and alert — 1986
2. •
   (slang) To keep one's cool.

   • Chill out, stay frosty, be cool. — 1991