Everyone in the cast of “Gossip Girl” is hooking up with each other – and Chace Crawford and Taylor Momsen are at the center of the latest smooching session.

A Page Six spy spotted the co-stars sneak away during their holiday party at Haven on East 51st Street to steal kisses in the corner, but Crawford’s rep denies it.

I’m guessing they are denying it because the girl is only 15 years old! Talk about robbing the proverbial cradle, Mr. Crawford is 23.

Taylor Momsen began acting professionally at age 3, with a national commercial for Shake ‘N’ Bake. In 2000 Taylor got the role of Cindy Lou Who in How the Grinch Stole Christmas.

Last week Ed Westwick and Jessica Szohr were kissing in an airport, and original “Gossip Girl” couple Blake Lively and Penn Badgley are still going strong.