The incomprehensible noise that occurs when someone attempts to talk whilst brushing their teeth.
After awhile, you may begin to understand this language, especially if the person is making hand motions.
Guy 1: MMPHHHMMNMNMHSHHSSPFTT
Guy 2: Dude I can't understand your toothbrush talk.
Guy 1: MMMPPSFHHFTSHHS -waves hands-
Guy 2: Ohhhhh, nah I already saw that movie last Friday.