The actual method of conception used in the Arnold Schwarzenegger film Junior. It wasn't mentioned much in the film.
The name is somewhat misleading, as it refers to punching someone in the rectum, not the vagina.
Martyn: Don't make me Sloppy Cunt Punch you.
Danny DeVito: Hold Still. BAM!
Dr. Alex Hesse: Oh I feel the baby, the baby!
Dr. Alex Hesse: Oh SHIT! Richter!!!!!