It's the pants. He's packing HEAT. Like seriously. He's also not "traditionally" sexy. In fact he's rather ugly facially, but he WORKS the sexy in attitude. I think that is his sex appeal, he's so confident and secure about who he is. I mean the man sported a Mullet, More make-up than a dime store hooker, high heels and glitter, GLITTER and was still oozing masculine confidence in that movie. Take that Edward Cullen.
http://knol.google.com