Let one´s hair down: relax, get comfortable; behave informally; rid oneself of restraints
Keep your hair on: Take it easy.
Tear one´s hair: to be anxious, frustrated, or angry. I was so nervous, I was about to tear my hair. I had better get
home. My parents will be tearing their hair out.
I let my hair down; Keep your hair on; I’m tearing my hair out