USC Professor of Neuroscience and Psychology, Irving Biederman, suspects that humor could feed the brain in the same way that intricate information does. It might be that way due to the fact that you need to interpret a joke, so you have to process distinct types of information. Not to mention...how good do you feel about yourself if you figure out a joke before you ask for the punchline? Best thing ever. Read more on how humor affects the brain from this article from The Healthy.
So, why are some jokes funnier than others? Because some jokes can be too confusing, too long or people just plain and simple don't see them as funny. Researchers did some actual digging and found the funniest jokes which you can find in this Reader's Digest article.
One of my favorites is:
A young boy enters a barber shop and the barber whispers to his customer. "This is the dumbest kid in the world. Watch while I prove it you."
The barber puts a dollar bill in one hand and two quarters in the other, then calls the boy over and asks, "Which do you want, son?"
The boy takes the quarters and leaves. "What did I tell you?" said the barber. "That kid never learns!"
Later, when the customer leaves, he sees the same young boy coming out of the ice cream store. "Hey, son! May I ask you a question? Why did you take the quarters instead of the dollar bill?"
The boy licked his cone and replied, "Because the day I take the dollar, the game is over!"