Jackpot!

A girl with dark hair and a light blue shirt stands with her back to the viewer at a carnival, then turns to reveal she has transformed into a monstrous creature with large crab-like arms, glowing yellow eyes, and sharp fangs, before lunging forward with her mouth open to reveal a large, sharp-toothed maw. The scene takes place at a carnival at night, with a crowd of onlookers reacting in shock.