Oh bugger... I thought I'd made it up.
Oh well.
(the_hammerhead_tart -- In love with a strict machine, Fri 4 Apr 2003, 17:41, archived)

I remember it from
The Brand New Monty Python Papperbok from donkeys years ago.
( moonbadger _/_/_/_/_/_/_/_/_/_/_/_/_/_/, Fri 4 Apr 2003, 17:49, archived)