From CripHumor:
When a fellow piano tuner from our company was ill, I was assigned to take over his assignment of tuning a piano in a young ladies’ boarding house. While I was at work, several of the girls strolled casually through the room in various states of undress.
The climax came when a pretty young lady, with startlingly little on, appeared to pay the bill. As I was handing her the receipt, she suddenly gave me a bewildered look, then fled, screaming, “That’s not our regular man!”
Turns out their regular man is blind!