Why did the chicken cross the road?

Q: Why did the chicken cross the road?
A: To get to the other side.

This is a very common joke. The reason why it is funny is because the joke opens in a manner that makes it apparent that it is a joke, but then ends with a punchline that is the actual answer to the question. This is an example of anti-humor. In this joke, the joke is actually the fact that it is not a joke.