Yea that happened to my friend after smoking a fat KB blunt and going to a concert.  He blacked out and sat down somewhere.  Even after experiencing mushroom's powerful effects i still consider marijuana to be an equally powerful drug.  It is so unpredictable and it really is different everytime, but a bit more merciful then mushrooms.

Dang that is frightning. My first trip i smoked  when the mushroom effects where wearing off, and all of the sudden i got so high. The most stoned ive ever been off weed i was blacking out. all my vision got darker and at one point i couldnt see anything but almost only darkness. i layed down and waited about an hour for the effects to go away. scince then ive never mixed smokeing with shrooms