There's nothing positive to gain by experimenting with massive doses of caffeine. Like any stimulant..excessive doses over time will cause an imbalance in your neurotransmitter levels, especially dopamine levels. People who abuse amphetamines have been known to experience a psychotic break (just like Mike Mentzer had). Using caffeine as an ergogenic aid early in the day for training or cardio is fine. Yes, high enough doses could cause hallucinations..but it probably wouldn't be pleasant as your heart would probably be palpitating. If you want to hallucinate, some Psyilocibin mushrooms would be a better option..and keep some zanax handy in case the trip doesn't go the way you want.