As seen on Keith Lemon's infamous 'Celebrity Juice' it's another word for Cunninglus. The way your mouth moves while performing this act produces a 'mott mott mott' action.
Phil: Hey Dave, did you get lucky with that skank you pulled last night?
Dave: Nah man, I was too pissed to do that business so I just motted out instead.
Phil: Nice, did you repeat yourself with 'MOTT MOTT MOTT' like Keith Lemon?
Dave: Yeah, she got freaked out and went home for some reason?
Phil: PAR
68👍 52👎