Dictionary

let one's hair down en · VERB

(idiomatic) To relax and enjoy oneself.
- 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 1982, George Jackson, “Down Home Blues”, performed by Z. Z. Hill:
- 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. 1981 February 14, Richard Credill, “Take Him By The Hand”, in Gay Community News, volume 8, number 29, page 5:
- 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 1962, Roy Bennett, Sid Tepper, “Relax”, performed by Elvis Presley:
Used other than figuratively or idiomatically: see let, one's, hair, down.

Spelling	Features	Source
lets one's hair down	Number=Sing, Person=3, Tense=Pres	lexicographic
letting one's hair down	Tense=Pres, VerbForm=Part	lexicographic
let one's hair down	Tense=Past, VerbForm=Part	lexicographic
let one's hair down	Tense=Past	lexicographic