I've experienced a bad high before. Once i smoked probably about 3 bowls out of my mini-bong and i went inside to chill. Well, for some reason i got really paranoid and i thought that my parents were calling me cause they smelled it on me. So, i got scared shitless and hid under my blankets. Soon, i heard them banging on my door screaming for me. It was horrible, it was really freaky and it was trippy, but not a good trip. I thought they really did find out. In the end, no one knew, and i was good after a 5 hour sleep. Shit was scary though.. bad trips are horrible.