Sir GalahadKing Arthur was in Merlin's laboratory where the good wizard was showing him his latest invention. It was a chastity belt, except it had a rather large hole in the most obvious place.
"Why this is no good, Merlin!" the king exclaimed, "Just look at this opening. How is this supposed to protect m'lady, the Queen?"
"Ah, sire, just observe," said Merlin.
He then selected his most worn out wand, one that he was going to discard anyway. He inserted it in the gaping aperture of the chastity belt whereupon a small guillotine blade came down and cut it neatly in two.
"Merlin, you are a genius!" exclaimed the grateful monarch. "Now I can leave, knowing that my Queen is fully protected."
After putting Guinevere in the device, King Arthur then set out upon his Quest.
Several years passed until he returned to Camelot. Immediately he assembled all of his knights in the courtyard and had them drop their trousers for an informal 'short arm' inspection. Sure enough, each and every one of them was either amputated or damaged in some way. All of them, except Sir Galahad.
"Sir Galahad," exclaimed King Arthur."My one and only true knight. Only you among all the nobles have been true to me. What is it in my power to grant you? Name it and it is yours!"
But, alas, Sir Galahad was speechless.