Dan wrote:

A few years ago I proved engineers are not known for their sense of
humour. I made my father, a retired engineer, an electric tack hammer. I
drilled a hole in the bottom of the handle, cut the end off a new
extension cord and epoxied the end into the handle. My father actually
plugged it in to see if the magnetic end of the head was affected. He
had some friends, several of whom had been engineers, over a few days
later and they couldn't figure it out either. My father is a guardian ad
litem and was goin to take the hammer to the courthouse to get x-rayed
to see if I had been flimflammed. Good thing I called before he did. To
this day he doesn't understand the joke behind electric hammers.

Dan, U.S. Air Force, retired

What? I don't get it!