Provide the cheerleaders with some clothes

"Hey, look," says Jasmine. "There's some clothes over there."

And there are. A whole stack of cheerleader uniforms, in green and white, sitting in a neat pile in the locker room. Provided by yours truly, of course. The cheerleaders are so grateful for the opportunity to get dressed again that they don't stop to think about where all these nice new clothes might have come from, or how some clever prankster might have sabotaged them. They just pull them on. Then Stella calls for silence.

"Alright," she says. "We're dressed. Now we want ****. And I know exactly where to start."

It's a long way across the campus to the headquarters of the chess club. A dozen nerdy-looking elf girls, in glasses and ponytails, jump out of their seats as Stella kicks in the door. "Alright, dorks," she shouts. "I know you know something. Who's ready to talk?"

"What?"

"Huh?"

"King to C4... hey, why is she here?"

The head of the chess club, a skinny bespectacled elf in a bulky sweater, steps forward. "Stella, get out! We told you to leave us alone after last time?"

"But you couldn't leave us alone, Verinda, could you? Don't think I don't know what you did."

"I don't know what I did!"

"This feud between the cheerleaders and the chess club has gone on long enough. We're going to end it. Right now."

"There isn't even a feud! You just bully us all the time!"

"Tha's right, nerds. Now prepare for the bullying of a lifetime. You think we wouldn't figure it out? A Shower Surprise Ogre is exactly the kind of thing a game-loving dork like you would come up with!"

"Shower surprise what? I have no idea what you're talking about!"

Stella steps foward, grabbing Verinda by the upper arm. The chess girls are getting nervous, huddling together for protecting as the cheerleaders advance on them. This is getting interesting. You could turn the tables by activating the booby-traps you planted in the cheerleaders' new uniforms, or you could wait and see how this unfolds. It's fun to watch cute nerd girls get bullied, but it might be even more fun to watch them doing the bullying.