A little girl asks her Mom, "May I take the dog for a walk around the block?" Mom says, "No honey, the dog is in heat." "What's that mean?" asked the child. "Go ask your Father. I think he's 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 Mom but she said the dog was in heat and said I should ask you".
Her Dad said, "Bring Susie over here".
He took a rag, soaked it with gasoline, and scrubbed the dog's rear end with it and said, "Ok, you can go now but keep Susie on the leash and only go one time around the block". The little girl leaves and returns a few minutes later with no dog on the leash.
Her Dad asks, "Where's Susie?"
The girl replies, "Susie ran out of gas about halfway down the block -and there's another dog pushing her home!