fire truck

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."