I found this while doing sermon prep. The original source is unknown but I found it here.
The drunk husband snuck up the stairs quietly. He looked in the bathroom mirror and bandaged the bumps and bruises he'd received in a fight earlier that night. He then proceeded to climb into bed, smiling at the thought that he'd pulled one over on his wife.
When morning came, he opened his eyes and there stood his wife. "You were drunk last night weren't you!"
"Well, if you weren't, then who put all the band-aids on the bathroom mirror?"