The act of a man pooping during a house party. A girl needs to then enter the bathroom with no choice but to puke between the guys legs while he poops. To seal the deal, the guy must request a blumpkin before she leaves the bathroom as a bribe for he will not tell anyone of what just happened.
Dave: What are you doing in here?
Alex: I need to throwup
Dave: Just puke between my legs
Alex: I don't want to, you'll tell everyone but I really need to puke.
Dave: If you give me a Bobbing for Brownies Blumpkin, I won't tell anyone