1.13 "The Thin Line Between Chuck and Nate"

The shadowy and unseen 'Gossip Girl' takes pleasure in reporting that Serena was spotted by one of GG's Web contacts buying pregnancy tests at a local pharmacy. Of course, on the Upper East Side, the truth is often even juicier and more scandalous than the gossip when Dan's sister, Jenny, learns that Serena was purchasing the tests for Blair who fears she might be pregnant from her trysts with Nate. But things get worse when Nate finds out that Chuck has been having an affair with Blair and both nearly come to physical blows, and Blair becomes ostracized by the rest of her clique as her reputation of a slut becomes more known. Meanwhile, Rufus, in an attempt to cheer himself up following his breakup with Lily, goes on a date with his art gallery sponsor, Bex, to a local bar.