Try this out, and experience natural hallucination. Stare at the center, keep your eyes still & look away when instructed. Don't worry, this isn't one of those lame "something pops up & scares you" videos. Try and give me a feedback...
Other link: Optical illusion - destroy your brain
Other nice illusions:
Lufthansa 747-400 and a United 757-200 - optical illusion
Charlie Chaplin Optic Illusion
Optical illusion - destroy your brain
How can be this be true? (Optical illusion)
Excellent pig illusion