Things are getting a little crazy down on the set of Gossip Girl in NYC.

Our photographer dropped by to see Chase, Blake and the rest of the gang in action…and up popped zany songstress Lady GaGa.

We’d heard rumors Poker Face crooner Lady G was due to appear on the show in a cameo role, and there she was.

GG bosses are remaining tight-lipped though about what exactly the part GaGa is playing, but lunatic pop star would be a good guess.

See more pictures of Lady GaGa below…