Doctor Joke

This one's a classic joke which many of you have probably heard before, but I guess it's a classic for a reason: it still is rather humorous, don't you think?

Doctor: I have good news and bad news.

Patient: Go with the good news first.

Doctor: You have 24 hours to live.

Patient: What!?! How about the bad news?

Doctor: Um... I forgot to tell you yesterday.

Also, I'm sure you've heard of the "Why did the chicken cross the road" joke. It's not really funny and it's really more of a riddle than a joke. Why do some comedians use this line even though a) it's a really old riddle and b) it's not even a joke? You tell me.