Annoying Things Customers Say

Working in retail, you hear many stupid and annoying things that customers say. To me, the stupidest thing they say is when they stand in front of empty checkouts and say loudly, “Is anybody serving here?!” My retort, could I make one, would be “Why, yes, there is, the invisible man on number 1 and the wizard boy in his invisibility cloak on number 2!” They can see no one is there, so why ask? It winds me up every time.