I'm going to bully a kid at my school with autism
Why would you be so mean to him?
Because he'll be a cool kid for a couple of seconds.
This wont make him become a cool kid, don't think that. It's just wrong to treat others badly, especially if they have a disability and can't defend themselves.
I don't give a shit if it's wrong or not.
You should try to put yourself in their shoes. I know that you would feel bad about yourself if someone mistreated you just because you had a disability.