XKCD has some very entertaining comics. Last week, I came across one that I particularly liked, “Good Cop, Dadaist Cop”:
A certain species of humor relies on the element of surprise. You may enjoy its greatest effect only once. Another, however, finds its power in the absurd, and from its fountain, you may indulge yourself many times. Happily, humorists often use both in their work to tickle us.