set one's hair on fire

Alternative forms

 * light one's hair on fire
 * run around with one's hair on fire

Etymology
Possibly from stories of Viking marauders said to have set their hair and beards on fire when running into battle in order to appear fanatical and fearsome.

Verb

 * 1)  To become wildly impassioned; to behave crazily.

Synonyms

 * freak out
 * lose it

Derived terms

 * hair-on-fire (adj)