This didn't happen to me, but to a co-worker. Seeing as how we love to discuss the intricacies of bizarre customers, here goes it.
Vicki is ringing up a customer buying a $18 blue ceramic bowl.
Vicki: "Did you want a box for this?"
Customer: "Yes, please. It's a wedding gift."
Vicki: "Oh, okay." Proceeds to peel off price tag, wrap the bowl in bubble wrap, and place into white box. Box bulges noticeably in one corner. Vicki holds up box. "Um, is this okay? The bowl's too big for the box but this is the largest box we have."
Customer: "Eh, that's fine." Pauses, and then adds: "I might be concerned if this was her first or second wedding, but it's her fourth."