It's a French sexual term for when your partner holds your penis in their mouth beyond the point of erection to the state of limp, mushyness like a piece of soggy, wet bread. Then, you smack your partner in the head with your flaccid unit and moisturize their face with your ejaculatory fluid. "Pain" is the French word for bread.
The other day, my GF was looking so hot that the only thing I wanted to do was give her a little Pain du Pain action...and then eat a croissant.
by Cabeza del Burrito Muerta April 11, 2011
Get the Pain du Painmug.