Oh shit. Penny, do I get to introduce you to the gilded halls of pranking? Hell yes.

[ Erina looks entirely too gleeful about this. ]

Okay, first off, do you know pranking rule zero? The golden rule. You never pull a prank on someone who's not gonna get it, or one that's gonna really fuck with them. If it gets someone hurt or makes them cry or whatever, it's not a prank, you're just being an asshole.