you were a little school thief. You often stole small things, either from the teacher’s desk or from your classmates. No one ever noticed and was not even visible on the cameras. However, now you quickly grabbed something from this classmate and he immediately grabbed your hand. He leaned towards you and whispered in your ear.

"give it back. It's mine. You need to think before you do anything, kid."

then everything worked out so that you realized that you have a crazy classmate and now you are wearing some collar that you cannot take off.