Serena comes into the PRADA living room with Rufus and D-Hump staring her down, and Rufus shows her the magazines, and Dan makes shitty inappropriate jokes as is his wont, and Serena immediately shifts into game face, giving Rufus her most Serena smile: "Rufus, I know I shouldn't have lied, but I was in Europe and I had just graduated, and I got a little carried away. And what happens in summer stays in summer. Right?" He's not sold, but basically because he thinks he's supposed to be acting stern and fatherly until she hangs herself.
"Look, the only reason I didn't tell you is because I thought if I did, you'd think I'd gone off the rails again." Rufus asks honestly if she did, and that care and respect that he has for her really comes through again. It's such an honestly nice note, you guys. It occurs to me that he's always pretty much thought she was great, actually. Even when he treated her like a bad influence it was usually about Lily and not Dan at all. Also: Serena never actually goes off the rails, so it's kind of a given, but she thinks before answering. "No. No, everything I said to you last night was true. I... I'm done." He nods and agrees to forget about it, and then smiles grudgingly. "And in what is perhaps an ironic twist... Due to your current social status, the Polo Society has asked if you will throw in the first ball at the match tomorrow." She agrees, and he runs off to notify them, saying that Lily will be proud.
When Rufus is gone she turns one of her patented Goddammit Humphrey looks on Dan, and he melts immediately, because way to replay the worst part of yesterday, but after shrugging it off Dan goes back to the usual: "There was one guy who was in a lot of those pictures with you who...Who was that?" She admits it was Carter Baizen, and says it got weird, and she took off. Realizing that she has said too much already, she takes that last little bit and twists it into an amazing lie, which is that Carter has become a stalker and is a dangerous person. This is amazing because it is balls-out, but also because Dan bears the scars and blowjob shame of Serena's last stalker, so he's the only person likely to believe it. It's grandiose. She begs Dan to keep Carter away from her at all costs and runs off, and Dan immediately calls Blair so they can join forces and fuck everything up like they always do. Meanwhile, Scott is fingering his birth certificate in a sinister manner at that same fucking coffee shop and talking to his mother about nothing whatsoever.