A businessman was strolling up the high street one day when he noticed that Little Johnny was wearing a red fireman's hat and sitting in a red wagon. Strangely, it looked like the wagon was being pulled rather slowly by a huge Labrador.

When he got closer to the kid, he noticed Little Johnny had tied a rope, very tightly, around the dog's...nether regions, which would obviously account for why the dog was walking in such a gingerly manner.

He looked at Johnny and smiled - "Son, that's a great looking fire engine you got there, but I'm sure the dog would pull you much faster if you tied the rope around his neck..."

"Yeah," Johnny replied, "but then I wouldn't have a siren!"