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 Little Johnny had a rope tied around the dog's testicles, which explained why the dog was walking so gingerly.

The man smiled and remarked, "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," Little Johnny replied, "but then I wouldn't have a siren."