(1) King, or the (2)dominator.
(i.e. 1- Just as the tyrannosaurus Rex is the dominator or king of all other dinosaurs and rex's whoever he wants. (i.e. 2- Just as you may have rexed your buddy in a game of Ping Pong.
(i.e. 3- You may want to Rex that chick who's V-card is dangeling infront of your jock.