1670s, shortened form of periwig. Meaning "person who wears a wig (professionally)" is from 1828. The verb meaning "to behave hysterically" (usually with out) is attested from 1955, from notion in to flip one's wig. Cf. dash my wig!, a former mild imprecation (1797), also wigs on the green (1856), Irish colloquial for "a fight or rumble" (because wigs are likely to get detached from owners in such an event).
Excellent; wonderful; great, neat: a real wig rock trio (1960s+ Teenagers)
nounblow one's top, flip one's lid