Customer: I want a pound of shrimp, but I want you to get a new box of bags from the back to put them in.
(I go to the back and emerge with a new box.)
Customer: No! That box is already open. Go get another. I want to watch you open it.
(I get an unopened box, open it while she stares at me, get a bag and put her shrimp in it. )
Customer: Much better.