Say you bought some clothes. Say the store forgot to ring up one of the larger-ticket items. Say you tried the item on again when you got home and decided that you didn't actually want it after all. Would you:
A) return the item to the store, explaining the mistake.
B) return the item to the store, telling them your husband lost the receipt. Return it for store credit. Smile.
I know which course of action I'm leaning towards.