Since there is already quite a bit of discussion about what effects dropping acid has on the human brain going on at this site right now (what have we come to?), here's a handy little guide from the Boston Globe that will show you how you can cause yourself to hallucinate drug free. The miracles of modern science. It also details how to make your cuts not hurt as much and a fun way to scare yourself into thinking your friend has just stabbed you in the hand, which is about as fun a way to spend an afternoon as I can possibly think of.