Errr... what type of stuff, paranoia, weird shit appearing out of thin air, could be an enviromental problem, any way the weed could have gotten laced with something, your not smoking out of a lead pipe right?

Such things as mercury and other toxic elements can be found in the darndest places, the bud might bring out the mental damage... But more than likely your friend worries about things and it can get verry overwhelming while high, just covering all the bases...