A man was walking on the sidewalk and noticed up ahead that little Johnny was wearing a red fire man's hat and sitting in a red wagon. It appeared that the wagon was being pulled slowly by a large Labrador Retriever.

When he got closer to the lad, he noticed that Johnny had a rope tied around the dog's testicles, which probably accounted for why the dog was walking so gingerly.

Smiling, he spoke to the little boy, 'That's really a nice fire engine you have there son, but I'll bet the dog would pull you faster if you tied that rope around his neck.'

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