wet fen Share definition Flag The act of urinating into the ass during anal sex. Dude, I had to piss bad but didn't feel like getting off the a train, so since Kate's a whore I just gave her a wet fen. wet fen by orignal wet fenner January 14, 2008 0 0 Get merch Get the wet fen mug. Buy Now — $32.95 See more merch