The Metamorphosis by Franz Kafka

At first he wanted to get out of bed with the lower part of his body, but this lower part—which, by the way, he had not yet looked at and which he also could not picture clearly—proved itself too difficult to move. The attempt went so slowly. When, having become almost frantic, he finally hurled himself forward with all his force and without thinking, he chose his direction incorrectly, and he hit the lower bedpost hard. The violent pain he felt revealed to him that the lower part of his body was at the moment probably the most sensitive.

The story of Gregor Samsa is one of the most widely known in the world of literature. From the first sentence, we know we are in a world defined very differently than our own, yet the   settings confirms that this is indeed the world we live in. Gregor has awakened transformed into "an enormous vermin." His exoskeleton and many, waving, "pitifully thin" legs give a hint regarding what kind of vermin he is, a beetle, bug or other shelled critter.

While we expect a tone of horror to accompany one's own discovery of this transformation, what we get instead is a strong sense of humor. Gregor is trying to get out of bed, and in the process strikes the "lower part of his body" on the bedpost.  While great literature is often serious in tone, this cannot be read without a wry smile. It recalls many episodes of America's Funniest Home Videos, the fathers being struck in the "lower part of the body" by a plastic ball bat, a kicked ball, an errant dog's nose. 

In this case, the humor is not Gregor's sense of humor, at least not in the sense that he sees the humor in the situation of himself being transformed into an enormous vermin. Rather, the source of the humor is in Gregor's denial of the reality of his transformation. He remains determined to get out of bed, pack his things, and head off to work. To introduce this pattern of denial, and especially the humor of these denials, Kafka uses that greatest of all physical humor jokes: a shot at a man's "lower part of his body."  

Ouch.

Kafka, Franz. The Metamorphosis. New York: Bantam Classics, 1916.