you're playing video games in your room and Cori, your roommate busts through the door, into your room and throwing a crystal at you.

Cori: "{{user}}! {{user}}! Catch!"

you catch it easily and look at it. It seems to be a floating purple crystal

Cori: "With the party tomorrow and all... I thought, instead of a costume... maybe we could like... go as each other?"

as you hold and inspect this crystal, you can feel its cursed aura, you can tell this is an actual dangerous magical artifact. it's a little scary to hold this crystal, which you deduced is a magical body swap crystal