Gretchen and Karen confront Regina at lunch. She's wearing sweatpants. On a Monday.
That means Regina can't sit with them, per the ridiculous rules they have about what to wear and when.
Regina doesn't take Gretchen and Karen seriously and says those rules aren't real. Karen and Gretchen lose their cool. The rules were real that time Karen wore a vest, for example.
Regina explains that sweatpants are all that fits her right now. Karen, Gretchen, and Cady sit in silence.
Regina leaves in the table in a huff. She bumps into Emma, who calls her a fat-ass. Ouch.
Gretchen and Karen start following Cady around like a pair of puppies, and Cady wonders if she's the new Queen Bee.
They want to know what they're doing that weekend, and when Cady says she has to go to Madison with her parents, the fact that nobody's telling them where to be and when simply does not compute for Gretchen and Karen.
Cady assures them that she'll try to get out of her plans with her parents, and they breathe a sigh of relief.
Cut to Cady and her parents having dinner. Cady lies and says she wants to stay behind to see Janis's art show. Ultimately, her parents decide to let Cady stay home alone for the night.
Cut to calculus class. Cady tells Aaron that she's having a small get-together at her house tomorrow night and he's invited.
She's super-Regina-y about it, calling him "biotch," and telling him to shut up, etc. It's safe to assume she thinks it's cute. It's not.
Cady assures Aaron that Regina won't be there, and he says he'll come.
The following evening, Cady's parents leave…and Gretchen and Karen pull up right behind them.
Cady's excited that Aaron's coming over. She got cheese and crackers for eight people, and she hopes that'll be enough.
It's not enough. Cady's "small get-together" is a full-blown house party à la every house party you've ever seen in a teen movie.
Lots of people. Lots of red Solo cups. Lots of loud music.
Cady's anxiety is off the charts, and she starts pounding shots. Not a good idea.
Regina and Shane are on the way to the party, and Regina's incensed. How dare Cady not invite her? She invented her!
Meanwhile, Aaron arrives, but Cady misses him. She wonders if Aaron's blowing her off—and keeps pounding the booze.
Regina and Shane show up.
Aaron wanders into Cady's bedroom. He sees a photo of her and The Plastics and grimaces.
He sees a photo of Little Cady on an elephant and smiles. Just then, Cady stumbles out of the bathroom. She's sauced.
Aaron thanks Cady for getting him to come out; he's wasted too much time being ticked at Regina for being such a liar.
Cady assures him that she'd never lie to him…well, except for this one thing. She's actually good at math.
She was pretending to be bad at it so she could talk to him, and now she's failing.
Aaron tells her that's stupid; if she wanted to talk to him, she should've just talked to him. Cady says she couldn't because he was, like, Regina's property. Predictably, Aaron's offended.
Cady stumbles to clear up the misunderstanding, telling Aaron to shut up, but she just makes it way worse.
Aaron tells her that she's just a clone of Regina. Yup; he's kind of right. Then, just as Regina busts in, Cady pukes on Aaron.
Cut to Cady chasing Aaron out into the street, begging him to stay. He keeps right on moving.
Janis and Damian pull up. This night just keeps getting better and better for our girl Cady.
Janis stands up, through the sunroof, and lays into Cady while Damian keeps reminding her that they having to go because he has a curfew.
Janis is kind of mad that Cady had a party and didn't invite them, but she's really mad that Cady blew off her art show to have a party and not invite them.
Janis and Cady have a huge fight. Cady says she couldn't tell Janis about the shindig because she had to pretend to be Plastic.
Janis tells Cady she isn't pretending anymore. She is Plastic.
Then Janis mocks Cady and her "awesome" party. Cady fires back: it's not her fault that Janis is, like, in love with her.
That's the thing, Janis says. All the Plastics think everybody's in love with them when, really, everybody hates them. Including Aaron.
Janis then asks Cady why Cady's still messing with Regina, even though their mission is over, and Aaron still isn't into her.
Janis answers her own question: It's because Cady's a mean girl.
Then Janis chucks her painting at Cady's feet and tells her she can keep it; it won a prize. And with that, Damian and Janis ride off.
Cady checks out the painting: it's of her, Janis, and Damian. Cady tears up.
Regina stomps back to her car, munching on a Kälteen bar, followed by Shane. He's surprised by her snack choice: Coach Carr makes he and the other wrestlers eat those when they want to move up a weight class.
They make you pack on the pounds like crazy, he says.
Regina screams, and screams, and screams, and eventually Shane just backs away and leaves altogether.
Regina continues screaming all the way home and into her bedroom where she pulls out the Burn Book and creates a cruel page all about… herself.