Ah, the classic Cyclops story.
Greek (hero?) Oedipus and his men were sailing home from war when they landed on an island where the Cyclops Polyphemus lived. They had no idea that this one-eyed giant lived there, and were soon captured by him. The Cyclops brought them to his cave where he also kept his sheep at night, and blocked the entrance with a heavy boulder that only he could move. He ate some of Oedipus' men each day, then rolled the boulder away to let his sheep out to graze. But the boulder would be rolled back into place, trapping the men in the cave.
Oedipus quickly came up with a plan. His men sharpened a large pole when the Cyclops was not around, and when the Cyclops returned at night Oedipus offered him all their wine in an attempt to make him drunk. According to plan, the Cyclops got drunk and fell asleep. Oedipus and his men then thrusted the pole into the eye of the Cyclops, blinding him. The enraged giant woke up in pain, but could not find the men as he was blind.
In the morning, the Cyclops would let his sheep out to graze as usual, but felt the top of each sheep that left the cave so that the men could not escape. Oedipus thought of this beforehand, and tied himself and the remaining men to the bottom of several sheep, allowing them to slip pass the blind Cyclops. Oedipus and his men then sailed away, escaping the island of the dreadful monster. (Oedipus then lived happily ever after because I am not going to explain what happens to him after that no sir not at all).
This comic is just a joke that Polyphemus sleeps face-down so that the men would be unable to stab his eye. He got some cake too.