To power clean a (usually intoxicated) person, then split jerk them and throw them off the top of a houseboat into the water. Usually done as a punishment for poor or unruly behaviour (such as knocking drinks out of partiers' hands), for threatening to fight (and actually fighting) inanimate objects, and for sucking at drinking games. Also sometimes done because fuck you that's why.
"If Jaime knocks one more beer out of my hand, I'm going to kemp the shit out of him."
"If Riley doesn't stop talking about how great the Liberal Party is, I'm absolutely kemping his ass."