The Topic: hello?

Actually, Serpentina, if that is your real name, the phrase "my bad" was in usage even during the 80s. Its usage began during "pick up" basketball games, mostly in urban settings, whereup one player, after missing an easy shot, would say "My bad" as a sort of handy shorthand for a more elaborate apology. The term's transition to more general slang use was greatly accelerated by its inclusion in the enormously popular film "Clueless" in 1995, however. So, since the excellent film "Wayne's World 2" was released in 1993, Garth's use of the term, while a bit unusual, is certainly not as "fucked up," as you would say.