This story comes to me by way of a friend of a friend, so I can't take credit for much more than just repeating it ... but I think it's worth repeating.
So this person goes into a certain fast food establishment and is waiting in line. The rather large woman ahead of her orders two buckets of chicken. Without thinking, the cashier asks, "For here or to go?"
The woman, shocked, berates the employee, asking whether the cashier actually thinks she's going to sit down in the restaurant and eat two whole buckets of fried chicken by herself.
In response, the cashier simply yells, "Bitch, I don't know your life!"