Similar to a mushroom slap
but with the added bonus of doing it after you've ejaculated and your penis is covered in semen.
Guy 1: So how'd it go with Julia last night?
Guy 2: It was awesome!... Up until she just walked out after I Cream of Mushroom Slapped her in the face...
Guy 1: Rough dude. Guess she just isn't into that kind of stuff.