Why do cancers act like spastics?

It's true with my little cousin even. When he gets furious his head tilts left and right almost foams and makes this weird spastic noise, like a herd of hyenas chewing flesh, why do they do that?

It's enough they look sad and miserable most of the time and a little loof like an aqua, but add to that their snappy disposition and mentally retarded behavior then I can safely suggest that they come across in the least as weird, and something is definitely not right with them.