Blair is off her game and the reason is simple. Chuck has decided to audit classes at Columbia, purely so he can mess with her. He got in by promising to donate a “Bart Bass Memorial Rotunda” to the university.

And mess with her he does. Blair wants to become influential business professor Martha Chamberlain’s TA, but Chuck beats her to it, then informs her that she’s also being shut out of Chamberlain’s class.

B tries to get in good with Chamberlain anyway by promising to set her up with a handsome suitor from Cyrus’ law firm. Again, she’s foiled by Chuck, who manages to waylay the lawyer with a room in the Empire and an escort.

He embarrasses Blair further by sending a woman in the lawyer’s place.

This Chuck-Blair battle ends up being something of a draw, since Chamberlain decides to swear off Columbia altogether after overhearing the pair outline their increasingly ridiculous schemes.

Still, says Chuck, he’s not through with his ex quite yet. In fact, he's just getting started. He says whatever she wants in this world he would take away. She responds the only thing that would make him happy is her love, but he lost that when he slept with Jenny.

Her words, unfortunately, give Chuck an idea. He’s last seen calling up the admissions office at Parsons, saying that he needs to speak with Tim Gunn about enrolling a new student: Jenny Humphrey.

Wait, isn’t Jenny still a senior in high school?

Serena, meanwhile, finds that she has bigger things to worry about than running behind schedule. Someone has leaked a false rumor to Gossip Girl, saying that S has an STD.

He’s pretty sure the story can’t be true, but Nate lets evil Juliet talk him into getting tested.

To further complicate matters, Nate drags Dan along with him as moral support. Someone takes a picture of D at Student Health Services and sends that to Gossip Girl. Vanessa then sees the pic and gets paranoid that her boyfriend and Serena slept together last spring.

Juliet, of course, is behind the rumor. She and her imprisoned associate are plotting to bring S down and leave her with “nothing.”

When Juliet runs into Vanessa and V confesses her worries about Dan, Juliet sees a golden opportunity.

At a party at Hamilton House, Juliet convinces Vanessa to nab Serena’s clutch from the coat check.

Then she tells Vanessa to peek at Serena’s email, ostensibly so that she can find out whether or not she really did sleep with Dan. Upon snooping, V is relieved to find that her boyfriend has in fact been telling her the truth.

Before she can return the purse, though, Juliet takes S’ phone and sends out a salacious email from Serena’s email account to Serena’s English professor. In the fake message, Juliet has S promise that she will give the teacher sexual favors if he stops marking her late.

The professor, of course, happens to be at the Hamilton House party and the Dean, who is with the prof, informs her that she could be expelled for sending such an outrageous email.

Vanessa overhears everything, and she tells Juliet that they have to speak up and save Serena. J, though, ends up pining everything on Vanessa, and the evidence - S' phone is in Vanessa’s purse, she had a motive, and so on - is so strong that everyone believes Juliet.

Vanessa packs an overnight bag and leaves Dan’s loft to spend some time with her parents. Serena, meanwhile, goes to a bar to drown her sorrows.

There, she’s greeted by a familiar face: a guy from Blair’s building that always steals her cabs, contributing to her lateness.