ESL Expression - Let one's hair down

Today’s topic: phrasal verb “let one’s hair down”, an informal way of saying to have a good or great time, enjoy oneself. However, this phrase is also used as practical action when someone actually frees one hair from a pony tail or hair bun.

Examples

"The colleagues couldn’t wait until 5 o’clock because they go to the local bar and let their hair down."
The colleagues were ready to leave their office and go home to have some fun.

The woman’s pony tail was giving her a headache, so she let her hair down. - Practical

“I’m going to let my hair down and celebrate!” shouted the birthday girl. - Expression