12/04/2008 at 08:00 AM EST
Vampire-playing Robert Pattinson admits he sometimes slips into character when he's out with the ladies.
"I've been known for a little nibble," he told reporters at the London premiere of Twilight
The movie, based on the bestselling novel by Stephenie Meyer, has become an instant hit with tween audiences. Thousands of screaming girls lined the black carpet Wednesday night for a chance to see Pattinson in the (undead) flesh.
Despite adoring fans, the single Pattinson, 22, tells PEOPLE he's not actively looking for a girlfriend. "I'm not like prowling around, no!" he laughs.
However his admirers' pickup lines have changed following Twilight
's success. "Now it's very different," he said, continuing in a high-pitched falsetto, "It's, 'Oh I'm such a big fan!' "
One woman who's definitely in Pattinson's fan club
? Costar Kristen Stewart.
But the 18-year-old actress did jokingly recall one action scene that sidelined the strapping star.
"He tried to pick me up ... and he pulled his groin," she said. "It was hilarious! He was hurt but he was laughing."
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