Bad Joke:
A driver was tired and took a break at a motorway service station. As he started to sleep, someone knocked on the window and asked the time. "It's 8:15" he answered.
He tried to go back to sleep and was almost there when there was another knock at the window. "What's the time"? "8:30" the tired driver answered.
He tried to go back to sleep again, but there was another knock on the window. "Could you tell me the time, please?" he was asked. "It is 8:45" the tired driver replied.
Then he wrote on a piece of paper "I do not know the time" and put it in the window. Having deterred people from asking the time, he then went to sleep.
10 minutes later there was another knock at the window. "Hey, there" the voice said, "it's nearly nine o'clock"!