Day & Night

A motorist, bogged down in a muddy road, paid a passing farmer
twenty five dollars to pull him out with his tractor.   After he 
was back on dry ground he said to the farmer, "At those prices, I
should think you would be pulling people out of the mud night and
day."

"Nah, can't do that..." replied the farmer.  "At night I haul 
water for the hole."