The phrase originated as a running joke on sci-fi
series Red Dwarf
in reference to the ship's emergency siren. It was, for some time popularized by fans of Red Dwarf and was later used by Red Dwarf star Craig Charles on his 1993 game show Cyberzone. Craig used the phrase in much the same context as on Red Dwarf (when the game show sirens were sounded) and it became a 'catch phrase' of sorts for Craig on the game show, but was also a reference to the Red Dwarf joke.
John Fashnu picked up the catch phrase after appearing on Craig's show 'Cyberzone' as a guest, and subsequently copied it for himself on Gladiators. This caused much upset amongst fans of both Red Dwarf and Craig Charles, not only because he had copied the phrase, but used it incorrectly as a personal 'catch phrase' of his own.