Reminds me of the story of the university halls-of-residence caretaker
person.
One day said person (used to being the butt of practical jokes) went
back to his room and
spotted the door ajar.
He looked up and spotted a well-balanced bucket of cold water on top of
the door.
Gingerly holding the door he managed to get a hand in and hold the
bucket upright
whilst he lifted it off the door down to safety.
The bloke sighed that the calibre of students in the halls had
diminished, if they thought
that this old trick was going to fool him.
So he walked over to the sink and poured the cold water away, only to
have his
feet soaked since the "belt and braces" students had also removed the
sink trap!

Mungo :-)