King Arthur was getting ready to go on a quest, but was worried about leaving Queen Guinevere alone with all the Horny knights of the Round Table. So he went to Merlin the Magician for advice. After explaining his problem to Merlin, the Wizard thought about the problem for a while and then told the king to come back in a week and he would have a solution to the problem.
The next week the King returned to Merlin returned to see the new invention. A Chastity Belt... except that it had a rather large hole in the most obvious place. "This is no good," said the King "Look at this opening. How is this supposed to protect the queen???" "Ah sire, just observe," Said Merlin as he pulled out an old wand that he was going to throw away. Merlin then inserted the wand into the hole in the chastity belt whereupon a guillotine blade came down and cut the wand neatly in two halves. "Merlin you are a genius, now I can leave knowing that my Queen is fully protected." Said the King. After putting Guinevere in the device, King Arthur then set out on his quest.
Several years later the King returned to Camelot. Immediately, the king assembled all the knights of the Round Table into the courtyard and had them drop their trousers for inspection. Sure enough every knight was either amputated or damaged in some way, all except for Sir Galahad. "Sir Galahad, you are the one and only true knight what is in my power to grant you??? Name it and it is yours." Said the King.
But Sir Galahad was speechless.