let one's hair down

let one's hair down (third-person singular simple present lets one's hair down, present participle letting one's hair down, simple past and past participle let one's hair down)

1. (idiomatic) To relax and enjoy oneself.
   • 1962, Roy Bennett, Sid Tepper (lyrics and music), “Relax”, performed by Elvis Presley:

     Cut loose, let your hair down honey / Unwind, turn the lights down low / Relax, let's uncork the stopper / Come to papa, come on let's go

   • 1982, George Jackson (lyrics and music), “Down Home Blues”, performed by Z. Z. Hill:

     All week long I've been keepin' my cool / But tonight I'm gonna let my hair down / And get down with these down home blues

• put one's feet up