This one is quite true - it was told me by the man to whom it happened.
A musician who, amongst other activities, reviewed pianola rolls for his local magazine in the 1920s, was visiting a lady friend in Devon, England. During the course of a pleasant evening, he felt the need to go to "the little room", as he told it to me.
"Ah, Geoffrey," said the lady, "it's outside in the garden." These places were often to be found in outbuildings at that time.
Geoffrey Higgins (a pupil of John Ireland) went out and found the hut, complete with moon-shaped cut-out in the door, entered it, sat down, and "committed himself", as he tactfully put it. As his eyes slowly got used to the moonlight, he discovered that there was no paper to be seen anywhere, but eventually he noticed the remains of an old pianola roll, hanging on a nail rather high up.
He did what he could in the circumstances, and then went back inside the house. "Oh, Geoffrey," said the lady, "I didn't realise that you were going to be a little while. I quite forgot to put any tissues out. I do hope you weren't inconvenienced."
"No, not at all," said the musician. "I'm just sorry that I took rather a long time; I was looking for a few bars' rest."
Topic: joke