Not Quite Getting What “Return” Means

Customer: “I’d like to return these ice pops.”

Me: “Okay, I just need to see your receipt.”

(I take the box of ice pops.)

Me: “…this is an empty box!”

Customer: “Well, we ate them. Some of them taste good, but some of them had a weird taste, so we threw them out.”

Me: “I can’t give you money back on something you already ate.”

Customer: “Why are you so difficult?! I’m never shopping here again!”