1237
Ask the wimpiest cashier to move 6 bags of very heavy dog food to the front, by hand, saying that the trolleys will crush it and only the natural shape of the human body could keep it in shape. Then act like a personal trainer and cheer them on as they carry it, yelling at them when they drop it or try to drag it. After all 6 bags are at the front, pause for a moment and then say, "Nah, I changed my mind" and just leave.