She helps you play some pranks

It's a perfect set-up. Emma Frost is in the classroom, lecturing a bunch of students on mutant history. You sit in the back row and watch as Kitty sneaks up behind her, using your powers to make sure nobody notices.

Kitty taps Emma on the shoulder, making her intangible. Her clothes remain solid, and they fall through her body, landing in a pile on the floor. She stands before the whole class, suddenly stripped completely naked.

It's a few seconds before she notices. She squeals and tries to grab her clothes, but Kitty's already pulled them down below the floor. She gasps, blushes, covers herself and runs out of the room, followed by the laughter of dozens of students. She's going to have to run all across the mansion to get back to her bedroom, without any clothes on.

Kitty gives you a high five. "I can't believe I haven't done that before!" she says. "So who are we going to prank next?"