Randy Orton is confident when wearing sparkling underpants and body slamming a 300-pound dude in the ring. But the WWE wrestler is more nervous about his acting talent, which will be on full display next year at the premiere of That’s What I Am, a movie starring Ed Harris and Amy Madigan. Many pro wrestlers have made the jump to the big screen, but usually their films were of the action genre. The move is part of WWE CEO Vince McMahon’s new marketing tactic of pushing his wild wrestling personalities to become real actors. McMahon’s created a film division of WWE, and his lineup of half a dozen movies features not wacky comedies but subtle ones, starring people like Patricia Clarkson and Danny Glover. In Knucklehead, which opens Friday, the wrestler known as Big Show plays a guy in his mid-thirties who’s never lived away from his Catholic orphanage. But WWE execs say the guys are natural performers, they just need a little acting training, like when Big Show learned how to cry.