Near the end of Shakespeare's "Hamlet," Hamlet takes a stroll with his friend Horatio. They come across two jolly fellows who are digging a grave in the yard of the palace.
Hamlet picks up a skull that has been dislodged by the digging. He is told by the gravedigger that this skull belonged to a man named Yorick, who had been the court jester of Hamlet's father, the King. Hamlet takes the skull and pronounces the famous line, "Alas, poor Yorick! I knew him." In some productions of the play, Hamlet holds the skull as if he is inspecting a melon to see if it is ripe!
Although this scene is full of jokes, it serves a serious purpose: it leads up to the next scene, in which Hamlet meets his death. Here, Hamlet comes face-to-face (literally and figuratively) with the idea of mortality (i.e., that we do not live forever). Yorick, who had been "a fellow of infinite jest" (a very funny guy) is now a sack of bones at whom "my gorge rises at it" (my stomach turns at the sight of him).
Although Hamlet is disgusted at Yorick's present appearance and odor, his inspection of the skull helps him to come to terms with his own mortality.