The first time I took shrooms, my friend tried to put on a movie, and i was so utterly terrified at the thought of watching it that i threatened to cut him if he put it on (weird, because it was a comedy)... but after that i figured out i was being an idiot and calmed down.

DXM though, i kinda agree... i can't think of any way that could really cause a bad trip for me. My buddy spent about an hour puking the last time we did DXM, and he still said it was a good time. Just seems like the kind of drug that doesn't lend itself to terror.