An exclamation that usually forebodes a sexual act, more than likely an unwanted one.
Depending on the context, it can be used interchangeably with DO NOT WANT
Gurlfran 1: Ugh, Joe tried to put his arm around me at the movie theater.
Gurlfran 2: BAD TOUCH, BAD TOUCH. D:
Gurlfran 1: Nah, it's chill, I cockblocked