ONAF
It is an acronym for One Night at Flumpty's and is usually used so you don't have to spell Flumpty.
Random dude 1: Have you played ONAF?
Random dude 2: You mean One Night at Flumpty's?
Random dude 1: Yeah, so have you played it?
Random dude 2: You mean One Night at Flumpty's?
Random dude 1: Yeah, so have you played it?