It's mean to yell at someone.
Harry is waiting for a cashier to bring him the food he ordered while his taxi waits outside.
Harry wants to let the cashier know that he is in a rush.
Harry flags the cashier down and lets him know that his taxi will be leaving soon.
Harry flags the cashier down and begins raising his voice, demanding his food quickly without explanation.
The cashier grabs the items that belong to Harry and brings them to him quickly.
The cashier refunds Harry and demands that he leave, as he is not abiding by the store code of conduct.