Also see blumpkin, reverse blumpkin, and the inherently messy double dumpkin.
For the rarest variation of all time, see cunnilumpkin decker.
Accidental: My girlfriend loves it when I go down on her and chow box, and sometimes she can be so pushy about it. The other day I needed to crap so bad, but she told me to shut up and suck her vulva. Just as she was about to climax, I lost control of my bowels and dropped the whole load in my pants. It was a perfectly timed reverse cunnilumpkin, although I could have done without all the shit in my favorite khakis.