Crazy in a good way. Same as to "go off" – to really get into something, especially on the dance floor. An expression of joy and abandon. It’s a phrase often heard in songs of the time as the singer or rapper invites people to "go beserk." Today we would say, "Turn up!" Eminem uses the phrase in his 2013 song "Berzerk" which samples several songs including two from the Beastie Boys 1986 album "Licensed to Ill."