The Judge's Pistol

The Judge's Pistol
One day Mel Martin stopped by the chambers of a judge with whom he had lunch appointment. As his friend changed from robe jacket, Martin noticed a shiny black pistol holstered to the judge's shoulder.
The judge was not a frearms enthusiast, so Martin asked him why he was carrying it. His friend said that because of recent threats he had borrowed the pistol from the repository of confiscated weapons. Holding it up,the judge said,"I chose this one because it's so mean-looking,yet it hardly weighs a thing. I hope I don't need it, because I don't even know how to load it."
"It's not hard,"Martin said,examining it closely."We can fill it at the water fountain on the way out."