Joke from a genealogical newsletter
This joke might be funnier if you are inclined to spend long hours pouring over obscure texts and indicypherable messages:
A sexton in England undertook a project to map all the graves in the churchyard and to create a complete record of the individuals buried there. After years of work and research he had identified all of the stones but one. The stone, flat on the ground and directly behind the old church, bore only the initials H.W.P. The sexton dug through every church record and could find no record of anyone with those initials.
One day the plumber was working on the old water pipes in the church and chatting with the sexton who proceeded to tell him with pride about his project and added that he was greatly troubled by the fact that one stone remained unidentified. The plumber asked which stone that might be and the sexton pointed out the flat stone.
The plumber smiled and replied that he could solve that mystery since he had placed the stone there himself -- H.W.P. marks the location of the Hot Water Pipe.