(1) When one gets caught doing something stupid, embarassing, or anything of a private nature by your parents. (2) Also, when one's parents call you and prevent you from doing something enjoyable.
"He can't do anything tonight because he got schrumpfed by his mom last night while he was mastrubating."
The scrumpter is the rare act of reverse road-head. The driver of a vehicle performs oral sex on the passenger of said vehicle while operating the vehicle at high speeds. Known only to occur when planned. Usually filmed simultaneously.
So I was in the car with my girl when she leaned over and gave me the scrumpter.