King Arthur was getting ready to go on a Quest. He was worried about
leaving Queen Guinevere alone with all those horny knights of the
Round Table. So he went to Merlin for some advice. After explaining
his predicament to Merlin, the wizard looked thoughtful and said to
come back in a week and he'd see if he could come up with something.

A week later King Arthur was back 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.
"This is no good, Merlin!" the king exclaimed, "Look at this opening.
How is this supposed to protect m'lady, the Queen?"

"Ah, sire, just observe." said Merlin as he searched his cluttered
workbench until he found what he was looking for. He then selected his
most worn out wand, one that he was going to discard anyway. He then
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!" said 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 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.