While Nightmare Chica is the primary threat, the Cupcake acts as her proxy. In FNAF 4 , if the player fails to check the hallway correctly, Nightmare Chica will send the Cupcake into the Bedroom to attack.
Another thought: Sometimes, in online communities, challenges or pranks take on absurd names. Could "Cannibal Cupcake" be part of a prank or a viral marketing campaign? The "verified" part might indicate the user is looking to confirm if it's a real product or just a hoax. cannibal cupcake wiki verified
The Verified Wiki entry advises: