Keep your hair on means calm down and stop getting angry. All right, keep your hair on.
It is British, informal and slightly cheeky, which is why it sometimes makes things worse. To be told to keep your hair on rarely calms anybody at all.
1phrasekeep your hair onCalm down and stop getting angry.
“Keep your hair on, it was only a joke.”
keep your hair on is a phrase.
Practised in Idioms