Taylor Lautner celebrates birthday with Kristen Stewart

'Twilight' hunk Taylor Lautner celebrated his 21st birthday by going bowling with friends, including his former costar Kristen Stewart. Lautner turned 21 on Monday, but had an early party in a private area at Lucky Strike in Hollywood on Saturday, reported Us magazine. 'Spring Breakers' actress Ashley Benson and Arnold Schwarzenegger's son Patrick were in attendance. The group of young A-listers enjoyed bowling while listening to music, and snacking on pizza, sliders and chips and guacamole. Wearing a backwards cap, ripped T-shirt, leggings and Converse sneakers, Stewart, 22, showed up late to the event -- a little after midnight -- with a small group of friends. "She was being fun and social, bowling and high-fiving. She and Taylor definitely seemed to be good friends and she was living it up," said a source. The celebration occurred just shy of his actual 21st birthday, and the source said he "drank nothing." "Taylor was super nice, very polite," the insider said of the actor. Stewart's boyfriend and Lautner's fellow Twilight costar, Robert Pattinson, was not at the party.