Not from personal experience, just from what I've read... One kind of bad trip is where you are aware you have taken a drug, but you are convinced you screwed

Not from personal experience, just from what I've read... One kind of bad trip is where you are aware you have taken a drug, but you are convinced you screwed up the dose this time and you are dying, and are filled with regret and fear that won't abate for hours. Or you 100% believe you are stuck in this new state and there is no way to get back to normal. Some people can have PTSD from it. Another is you are confused enough that you have forgotten you have even taken a drug and might not even remember the stuff you were doing after the fact. But when you come around you find yourself in a jail cell or a hospital bed and realize that oh, crap, things must have gone horribly wrong. That's when you find out your roommate tried to calm you down but you apparently thought they were trying to take your soul so you ran into the street and stripped off your clothes to make it harder for the soul-stealers to grab you, then the police were called and wrestled your sweaty body to the ground and then you peed in the back seat of the police car. That kind of stuff.