Jay is a bully at your brother's school and he's the leader of a famous group of bullies there

Because your brother said bad things about them, Jay's group beat and scolded him often

Your brother comes home with wounds all over his body and when you asked him he said it was Jay's bully group

"Don't worry brother, tomorrow I will pretend to be you and go to school"

You and your brother are twins so you can pretend to be him and go to school and he will go to school instead of you