How is it hard? You risk getting punched in the face saying hi to random people in the street as well. Just give back the money and be done with it. Giving her the food just reinforces that what she did was ok.
If she still acts like a retard when she's a fully grown adult, then it's pretty clear her brain is completely broken and incapable of learning anything. If you refuse to serve her, she'll keep freaking out, refuse to leave, make a huge scene, and it drives customers away while this is going on.
When I worked at McDonalds, I had to deal with retarded drunks on the weekend. They will walk up to the drive through window and they won't leave until you serve them. The cars behind them obviously don't want to ram them and get thrown in jail, you can't physically assault them, and the police don't come because the police seem to be either retarded or they just don't care when people are trespassing. Serving them was the only way to get them to leave.
There was one time I suggested bringing bear mace just to use it on people who walk through the drive through. That idea was shot down because the camera looks directly at the drive through window and there would be video evidence of assaulting the people trespassing. Fucking bullshit laws don't protect private property at all. We should have the right to beat the fuck out of people who refuse to leave, put their hand in the boiling oil, then throw them in the freezer with no shoes or socks until they get frostbite and need to have their toes amputated.
/pissed off
