see chav, a chach is that guy who comes to the club with a vest and no shirt under it, gold chains, and fake tan. he thinks he rules and tries to hit on you blatantly. term may have originated with Chachi from Happy Days. Example: I can't believe that guy shaves his chest! What a chach!
Meaning of CHACH in English
Slang English vocab. Английский сленговый словарь. 2012