Physiology of The Cheat
From Homestar Runner Wiki
The physiology of The Cheat is indeed mysterious. Although it is one of the great mysteries of the Homestar Runner universe, an in-depth and detailed look at the anatomy of The Cheat was published in The Journal of The Cheat Science and Medicine.
 External features
One of The Cheat's external and more easily observed features is his teeth, which includes one gold tooth (also one of the internal features). Although only four teeth are visible on the outside, it is revealed that The Cheat has five total. The Cheat also has yellow and black fur with about 30 black spots visible at once.
 Internal features
The Cheat has 18 or 19 bones (if the Skelebrate is considered one bone), which are probably fairly sturdy given the amount of kicking he's received.
The Facebone is probably The Cheat's equivalent of a skull, and most likely holds his brain. It features five teeth, all on the top row of The Cheat's mouth (four regular teeth and one gold tooth). It also has the "for seeing" sockets, where his eyes go.
The Cheat's chest contains the aptly named "organ" and "tube" (their function is unknown), and six independently supported ribs.
 Sclipula and Ulterior Sclipula
A sclipula is a bone which serves as some kind of leg or leg-like structure. It is accompanied by an ulterior sclipula, also a bone and similarly shaped to a sclipula. The sclipula always faces whichever way The Cheat is facing and the ulterior sclipula always faces towards The Cheat's back. The Cheat appears to move by shuffling the sclipulae. Its name is derived from "scapula".
The Cheat's left arm has two bones and the right has only one visible bone (the other is either obscured or doesn't exist).
The Cheat also has two clusters of nerves (or possibly veins; though this is unlikely as they are green): one coming from the bottom of the facebone and one coming out of the back of the facebone and extending into his left arm-like structure.
Apparently, The Cheat can survive with one pulse every 4.45 seconds, even after being bombed with two or three roach foggers in bedtime story.
The Cheat has only two organs and no circulatory system, and if one of the organs is the brain, then The Cheat might not use any form of blood. The Cheat clearly has nerve endings. His nerves dangle out from below the unlabeled brain-like organ in his head like roots. Given the location of the other organ, and the fact that it has a tube extending from it to the mouth, it could possibly be the stomach, as he can eat and drink, or some sort of respiratory organ, as The Cheat has been inflated with helium. On the other hand, the position (behind the ribs) and appearance of the organ might be the heart, although that too seems fairly impossible due to the fact that there are no blood vessels. As Strong Bad said: "The Cheat's physiology just plain baffles me."