Worlds collided at Taylor Momsen's Sweet Sixteen last night when NYC Prep's Sebastian rubbed shoulders with the man who plays his fictional counterpart, Chace Crawford. Sebastian, blonde locks aflutter, had just come from PC Peterson's charity event. "He's a really nice guy, actually, despite what he may come off as on the show," Sebastian said of his world-weary co-star. The whole cast has bonded since wrapping, according to Sebastian. "We all know each other better [now]." And the Kelli-Taylor love triangle? "It was just fun." But then another wall came down: Sebastian reads the recaps! "Is that the one that picks a winner?" he checked. Yep — and we reminded him that he even took home the honor once. "I'm very proud," he said. "But I'm a little pissed off, actually, because Cole is always the 'auxiliary winner.'"