Gossip Girl sweetheart Leighton Meester cozied up to her boyfriend and recurring guest star Sebastian Stan (Carter Baizen) at the Parsons Fashion Benefit 2009 pre-party at the Calvin Klein Collection on Thursday, April 2, in New York City.

Here's the couple looking quite cute together ...

Earlier in the day, the 22-year-old taped an appearance of Late Night With Jimmy Fallon at the Studio 6B in Rockefeller Center. Her birthday is next week (April 9) so Jimmy and the audience decided to throw her a surprise party of sorts.

Follow the jump to see Leighton's "birthday" arrival on the program and the rest of her funny interview on Late Night, which includes some personal stories as well as a clip from the next new Gossip Girl episode, "Seder Anything" ...

[video url="http://www.tvfanatic.com/videos/leighton-meester-on-late-night-with-jimmy-fallon/" title="Leighton Meester on Late Night with Jimmy Fallon"] [/video]

[video url="http://www.tvfanatic.com/videos/leighton-meester-on-late-night-with-jimmy-fallon-part-ii/" title="Leighton Meester on Late Night with Jimmy Fallon (Part II)"] [/video]

She's awesome. Leighton Meester doesn't turn 23 until April 9, but as you can see in the photo below, Jimmy Fallon decided to get the party started a week early!

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.