Adam Brody and Leighton Meester do the walk of shame!

Adam Brody Leaves Leighton Meester's House After Relationship Reveal: Picture

Brody was photographed leaving Meester's home in L.A. on Wednesday, Feb. 6. The two met on the set of the 2012 dramedy The Oranges. "They were always close and friendly," an insider says, noting that the pair would hang out on occasion during shooting for the film. - US Weekly

And from ENEWS  
Leighton Meester Hides in Adam Brody's Backseat, Still Gets Snapped by Paparazzi

"Why so shy, Leighton Meester The Gossip Girl star tried to hide from the paparazzi in the backseat of Adam Brody's car Thursday.

The former O.C. star looked bemused as the brunette beauty ducked for cover. Although the duo is clearly trying to downplay their relationship, it's reportedly been going on for several weeks. According to Us Weekly, they even traveled to Bangkok together earlier this week.

sources: 1, 2, 3