My only really bad expirience with pot was my second time. I was 14.
I live in cali, and my brother is really into drugs, has a bunch of connections all over the state.
He had gotten ahold of the most potent pot he'd ever seen.
The night was great, he did a shotgun to me, one HUGE blast of smoke. I barely remember that night. I remember standing on my street, looking up at the stars as faces appeared out of thin air. I realize now, I was too stoned to really enjoy it, to really KNOW how good I was feeling. Just gone.
Well, the next morning, I was still high. 12 hours later and I was still pretty baked. And then I had to go to my house in order to get ready to spend the night at a friends. And then everything just went downhill.
Massive Paranoia. I couldn't eat, my heart felt like it was shriveling into itself. I was shaking constantly. Somehow I managed to pull it together in front of my mom(psycho bitch, mainly the reason I was paranoid), and when I arrived at my friends house, I just laid down on one of their beds for two hours. I was so freaked out.
Moral of the story... sometimes short highs can be a blessing. And long highs can turn into hell.