Bitchin (often written bitchin’) is old American slang meaning “really good” or “cool” — which is the opposite of what most students guess when they see bitchy. It was cut down from bitching. You hear it in films and songs from about the 1960s to the 1980s, surf and skate talk, and from people quoting that time for fun. Younger people do not praise things this way much now, except as a joke. It is too casual, and a little crude, for class or for anyone you do not know well. Though actually, if you only know bitch as an insult, this word will trick you: here it is a compliment.

超讚的（舊式美國俚語；意思跟 bitchy 相反）