Worst 'trip' I had was when I was at a friends apartment. I got a little over an 8th of some SHIT weed for free from a friend. I decided to smoke it. I smoked the entire 8th and just got a little stoned. Went to taco bell, ate an ass load, came back to the apartment, smoked 6 Djarum Black's (cloves) in a row, and then ate some Ramen. I started to sweat like a mother fucker so I went outside on the balcony, I sat down and started to chug some water but I eventually threw up hard core. Bean burritos and ramen everywhere! I also had a couple beers which didn't help. And I had been living off of ramen and taco bell for a while which didn't help my cause either. I threw up because I ended up getting nicotine poisoning thanks to the Black's and had a sodium overdose thanks to the Ramen. After I was done throwing up I drank some gatorade (remember to have gatorade around if someone OD's on sodium, it'll save lives) and then had an awesome night after that. After that one time I've never thrown up while stoned.
But you all do know that with very high doses of THC, weed is considered a hallucinogen... I have tripped before off of a lot of hash and some nice ass bud.
The story for that was it was my guys b-day. I had just gotten off work and met him in the parking lot. We hot boxed his car with a bowl of trainwreck and bubble hash made from shiskaberry on top. We smoked 4 bowls of that (I hadn't been smoking for 4 months when we did this) and I was tripping HARD. Like I saw fucking colors everywhere, shapes that spun around and morphed into statues, tunnels that I would fall through, and all the time I couldn't stop fucking laughing. I almost threw up that night but never did. It was amazing.