1. During the act of sexual penetration with a female, the male pulls his penis too far out of the female's vagina, and accidentally rams it into her anus instead during the next thrust, accidentally having anal sex. Usually VERY unpleasant for the female involved.

2. Also could mean the sour/surprised face one would make when being rectally penetrated suddenly.

the thing that you don’t have when you’re phones percentage is over 20