When a man gives a girl anal sex and while they are performing sex the man is dunking the girls head in the toilet! When the man lifts the girls head out of the toilet the man slaps the girls head with his dick.
Easiest example is that when your in a bathroom fucking a girl, DUNK her head over and over in the toilet and thats what a Porcelin Rim Job is!!
by TBone_NJ/HI December 11, 2009