A "politically correct" alternative to "motherfucker", apparently for using when you want to swear at a woman. (Yes, apparently, you can be PC and still swear - as long as you don't imply a masculine standard of sexual normality by using male-gendered swear-words against women).
It implies the "engulfing" of the dick in the fanny.
Actually, I think this is quite a cool insult, PC or not. It is especially good because you can use it against PC people.