Do not disturb sign joke

A person checks into a hotel for the first time in his life, and goes up to his room.

Five minutes later he calls the desk and say, "You've given me a room with no exit. How do I leave?"

The desk clerk says, "Sir, that's absurd. Have you looked for the door?"

The person says, " Well, there's one door that leads to the bathroom. There's a second door that goes into the closet. And there's a door I haven't tried, but it has a do not disturb sign on it."