Taking a chance on the pizza, you open the pizza box and see a completely untouched pizza, or at least not eaten. Taking the pizza and eating a couple slices, you close the box and continue onwards, feeling full enough to continue on. Not filling up to feel sluggish, you ate just the right amount.
You make your way to the park exit, when you feel a weird tingling in your gut. You moan as your stomach churns. Feeling an odd pinch above your butt, you scramble to the nearby bathroom. Checking to make sure no one is in there, you turn to see yourself in the mirror. Immediately you notice a tent in the back of your pants, slowly snaking down your butt towards the back of your knees.
Popping your pant’s button and unzipping its zipper, you pull it down enough to see a long pink rat tail hanging over your panties. It snakes and curls as you examine it. A rat mutant must have fouled the pizza or the water in some way.
You are transforming by the mutagen!
You need to hurry! Perhaps medical staff beyond the city blockade will have something to counter act the mutagen. Hopefully they can figure out something to shrink or surgically remove your tail. You have to hold out hopes for something. But if you don’t get to them before you change completely, it won’t really matter then.