Fred Cisin wrote:
  Left handed threads on flammable gases are an exercise
in Darwinism.
 Think about the guy with a cigarette in his mouth who smells gas, so he
 turns the gas fitting clockwise. 
I suppose I like to think that nobody who isn't trained in the equipment would
be allowed to mess with it - but if they've got a cigarette dangling from
their mouth at the time then they probably deserve everything they get :-)