After a long and tiring drive throughout the night…
… the driver decides to pull over on the side of the road to take a nap.
A man knocks on the car’s window and this wakes the driver from his sleep. The man asks the driver what time it is.
The driver looks at his watch and replies, “It’s 4:30am” and goes back to sleep.
After a while, another man knocks on the car’s window and wakes the driver from his sleep. This man also asks the driver what time it is.
The driver replies “It’s 4:57am” and goes back to sleep.
Sure enough, after a while, again, another man knocks on the car’s window and asks the same question.
The driver, now annoyed, replies, “It’s 5:20am”.
He picks up a piece of paper and writes in bold letters, “I do not know what time it is”, sticks it on the car’s window and goes back to sleep.
The driver is again woken from his sleep by a knock on his window.
The man knocking on the window says,
“It’s 5:35am, you’re welcome”.