Actor Paul Rudd, star of "Role Models," which opened Friday, just shot a PSA for Philly-based Big Brothers Big Sisters. "I'm Paul Rudd. In my new movie - 'Role Models' - I play a misguided mentor," begins the spots that can be heard online and will also be aired on radio nationwide. "It's R-rated comedy. And the truth is - we're making light of a very serious subject. I love the concept of these one-to-one relationships - what it does for the kids and the adults. That's why I'm a big fan of Big Brothers Big Sisters. They change how kids grow up - helping them beat the odds in school and life." The spot can be seen online on the BBBS Web site...Speaking of "Role Models," its director, David Wain, will be back Nov. 30 playing at Glenside's Keswick Theatre with his comedy troupe, Stella.