I have had some bad experiences with hash and just plain smoking too much premium stuff. One time, a friend of mine and I got pulled over by the cops, and we had to swallow enough hash to get high for a month. I was messed up for 3 days, I couldn't go to work, I couldn't even go to the store to get beer, it was impossible to do all the preparations necessary for that 1/4 mile drive, at one point my left leg became weightless and just stayed up in the air while I laughed for 30 minutes straight so hard that I was crying and I couldn't breathe. I also had weird daydream hallucinations like my girlfriend walking towards me sticking her foot long tongue out at me while twisted goat horns sprang out of the side of her head. Of course, when I pulled over, the cops just went past us on their way to some emergency or something. They weren't pulling me over.

I have had some similar experiences with really strong weed. I think a lot of the time it is people growing a really strong strain but maybe they are spraying insecticides on it right up to or even after harvest. Nothing would surprise me.