Walter's gone to a conference for the weekend, and Bianca's decided to throw a rager, much to Kat's annoyance. She's in charge, after all. But Bianca's careful to take pictures of each room to make sure everything is back in place before dad gets home.
The party kicks off with the arrival of Chastity and her cheerleader entourage, followed shortly by the football team and a spiked watermelon. Kat's busy trying to keep the house from getting shredded as more and more people show up. Chastity sets Bianca on Joey distraction duty so she can flirt with some college boys who've crashed the bash.
Kat's busy handing out designated driver wristbands when Patrick appears. He's there to explain what happened at the dance, but Kat doesn't want to hear it. He gets her alone long enough to explain, but she still doesn't care. She tells him he's just bad news, and he leaves in a huff.
Cameron's sitting outside by the pool, snacking on watermelon while he waits for the right moment to apologize to Bianca for messing up her Fall Fling plans. Uh, too bad no one told him the melon's spiked.
With the house brimming over and her anger doing the same, Kat says what the hell it's not her party. So she joins the fun. And the drinking, much to Bianca's annoyance. That's OK. Bianca can handle being responsible for one night, right? Wrong.
Kat turns into a very rambunctious (and kind of embarrassing) drunk. She hangs with the cheerleaders for a bit before getting her risky business on and bringing the house down with her karaoke rendition of "Straight Up." Bianca sends her outside for some fresh air ... where Kat finds Cameron, who has no idea he's drunk. Really drunk.
Joey's not as dumb as Chastity thinks he is: He sees her flirting with the college boys, and they have a huge blowout in front of everyone. Afterward, Bianca tries to console him as he sits in a corner, ruining his model figure with a bag of chips.
Back at the pool, Kat's drunkenly sympathizing with Cameron. Buy Bianca something sparkly, she suggests. She also thinks that, deep down, Bianca wants to make out with him. Wait, are you sure you don't mean you want to make out with Patrick, Kat?
Inside, things are getting out of control. The toilet is backed up, and people are throwing knickknacks around. You wanted a party, Bianca? You got one. Cameron decides to be brave and lay it all on the line for Bianca. He tells her he's in love with her, and he's not gay. Bianca turns him down as gently as she can but thinks maybe they should talk about this when he's sober. He thinks they should never talk about it again if that's the way she feels. He leaves all broken hearted.
Bianca tries to get Kat to help her end the party, but big sister's busy being drunk on the phone with Paaaaatrick. So Bianca tries to end it herself but fails miserably. Joey takes pity on her and clears the house in seconds flat with a clever ruse. Suddenly, filled with success in an empty house, they're lip locked! Hey, you can kiss your cheerleading career goodbye too, Bianca, if Chastity finds out.
The next morning, Kat wakes up on the living room floor of a magically spotless house. She's more than a little hungover, and "I love Patrick" is written on her arm. Bianca gets her upstairs just as Walter strolls through the door, none the wiser. Or is he?
Turns out dad's smarter than his girls think. He hid a spy camera in the house before he left, and now Kat and Bianca are in for a treat: a four hour "movie night" on the couch with dad, so he can enjoy the entire party with them.