let one's hair down

(verb) to relax; to behave informally.

Letcho hair down, dog!

let one's hair down by Fangsta March 18, 2003

to let one's hair down 

In general: to leave behind one's inhibitions or to behave in a way that is free from social limitations or any code of conduct.

(to let one's hair down)
Corrine Bailey Rae, Song:
Put your records on
Girl, put your records on, tell me your favourite song
You go ahead, let your hair down
Sapphire and faded jeans, I hope you get your dreams,
Just go ahead, let your hair down.

to let one's hair down by Pentametrics August 23, 2008