I sometimes pull my girlfriend's parking brake up harder than she can pull cause I think it's really cute later on.
You are making her scared on purpose? That can't be safe.
I just love her being all shaky from being unable to move
You are a person who loves to taunt others, that is in your blood. Do you realize this is a sadistic way of thinking and doing things? You better get that checked out by a professional, or your life will be lonely soon after your girlfriend leaves you for this problem you have.
I just wanted to harass her since it is fun.
I am sure she doesn't appreciate the harmful teasing. She isn't going to want to stay with you if you are putting her in danger. Find another way to tease her that you both could laugh at and have fun doing.