B-Days and BFs

Mary-Kate and Ashley Olsen may have been booing along with the audience at Kanye's performance -- the twins spent their 22nd birthday rocking out at Bonnaroo. But they were only in Tennessee for a hot minute. By Monday, Ashley was back in New York, just in time to make her first public appearance with new BF Justin Bartha (you know, the hottie from National Treasure) at a movie screening. "They huddled close together most of the night," an insider tells Page Six. Ashley better keep her hands on this hottie -- he's booty worth keeping!

NEXT SLIDE