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, “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

   • 1981 February 14, Richard Credill, “Take Him By The Hand”, in Gay Community News, volume 8, number 29, page 5:

     He should help himself before he tries to help someone else. If he's afraid someone will know him he should move to a new residence and let his hair down and join us swingers.

   • 1982, George Jackson, “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

2. Used other than figuratively or idiomatically: see let,‎ one's,‎ hair,‎ down.

• put one's feet up