You shouldn't treat cashiers like they are trash.
Sandy is not feeling well, but she has to stop by the pharmacy after going to the doctor.
Sandy wants to pick up her prescription.
Sandy picks up her prescription and hands the cashier the money.
Sandy tells the cashier to go get her prescription immediately and then throws her wadded up money at the cashier.
The cashier tells Sandy thank you and that she hopes she feels better.
The cashier is offended because of Sandy's very rude behavior.