Little Johnny's Toothbrush
Little Johnny came screaming from the bathroom to tell his mother he'd dropped his toothbrush in the toilet. Johnny's mother fished it out and threw it in the garbage.
Little Johnny stood there thinking for a moment, then ran back to the bathroom and came out with his mother's toothbrush. He held it up and said with a charming little smile, "We better throw this one out too then, 'cause it fell in the toilet last week!"