The hunky Twilight star, who plays Carlisle Cullen in the films, exclusively told Yahoo! omg! that he and Kellan Lutz (Emmett Cullen) got up to lots of mischief. He said: "Kellan Lutz and myself were probably the biggest pranksters. "[We did] lots of crank calls to people. We'd get bored sometimes so we'd do crank calls." And Peter told us about an incident involving a certain Robert Pattinson…