A little girl asked Mum, "May I take the dog for a walk around the block?"

Mum says, "No, beacause the dog is in heat."

"What's that mean?" asked the child.

"Go ask your father. I think he is in the garage."

The little girl goes to the garage and says, "Dad, can I take Susie for a walk around the block? I asked Mum but she said the dog was in heat and that I should ask you."

Dad said, "Bring Susie over here."

He took a rag, soaked it with petrol, and scrubbed the dog's behind with it and said, "Ok, you can go now but keep Susie on the lead and only go once around the block."

The little girl left and returned a few minutes later with NO dog on the lead.

Dad asked, "Were's Susie?"

The little girl replied, "Susie ran out of petrol about halfway down the road and there's another dog pushing her home."