Dalmation in a fire truck.

Johnny and two friends were walking along when a fire truck came down the street, its sirens wailing.  On the front seat was a Dalmatian.  “The dog is there to keep the people away from the fire while the firemen put out the fire,” said one of the boys.  The second boy said, “No, the dog’s there to give the firemen good luck.”  Then Johnny said, “You’re both wrong.  It’s the dog’s job to find the hydrant!”