Your all-time favorite hallucination?

[Jackalope]

I used to dabble in psychedelics. Take enough LSD or mushrooms and it -will- completely alter your perception of the world.

I watched my best friend's head cave in on itself, and then poof back out to normal, only to repeat the process over and over. The rest of my perception was equally bizarro.

I suspect that the disinhibition of neuron activity simply gives the brain more input than it can process and interpolate coherently. In football terms, your brain then punts.