Seen in uk.tech.digital-tv but I just had to share it with you. Written by
Bill Wright. to whom all credit must go.

The teenage daughter at this house was in a strop because the water in her
en-suite (!) was taking a while to run warm. The plumber tried to explain
that
there was quite a long pipe from the boiler to her private facility, and
without listening at all she snarled "Look, is there some law or something
that
says I have to wait for hot water?" Quick as a flash the plumber said "Yes,
it's one of the laws of thermodynamics, but I'll see if I can get it
repealed
for you." That plumber is my hero.

Peter Crosland