You get a feeling that you're making a bad decision, but you're making it anyway. With speed you didn't know you had, you lunge at the mousegirl, reaching for the gun, hoping to surprise her so she doesn't use it on you. She gives a high pitched squeak of surprise, and unfortunately for you, pulls the trigger instinctively.
A jolt of pain shoots through you, and you instantly fall to the ground. You start to black out, and the last thing you see before you fall unconscious is the mousegirl kneeling down, having dropped the gun, and bringing her paws to cover her mouth in shock....
When you wake up, something is very different. You're still in the classroom, and lying on your back now, that much is obvious. However, it's from a very different perspective. Propping yourself up on an elbow and looking around, you realize with a shock that you're lying on one of the tables... And you're tiny! Somehow, you've shrunk, but you can't easily tell your current size. As you lie there, propped up on an elbow, stunned at your current position, you hear a very quiet voice from behind you.
"Oh... You're awake," it says, sounding glad yet sheepish. You look towards its source to see the mousegirl sitting on a chair at the table's side near you, only now she's giant compared to you. You stare up at her, marveling at her size, and the huge bright blue eyes gazing down at you.
"What... Happened?" you ask, stammering.
"Okay, confession time... That gun was a shrink gun. And I just shrunk you."
"I figured that out myself. How small am I though?"
"Well, I had it set to..."