I want to barrel into the ball girl, sending her flying.
This can really hurt the girl. What is your reason for wanting to do this?
The ball girl has been being rude to me as I cheer for my team.
If the ball girl upset you, you should talk to her or someone in authority. You should not take out your anger in a way that will hurt the ball girl.
I just wanted to touch her ass.
It is not a good idea to hit the ball girl no matter what your reason may be in all honesty. If your motivation is just to touch her butt than that is even worse. Hopefully you understand why it is a bad idea to go through with touching the ball girl.