I've only been smoking for about a year now and there's a couple instances where something went wrong.

One time I was smoking with some buddies in this neighborhood we live near. I wasn't comfortable at all in this setting because we were all out in the open and shit. So we smoked and I was paranoid as fuck. So I agree with the guy that said you should definitely be in a comfortable surrounding.

Another time I smoked with my bud and we got some food after that. I don't know if it was the food or what, but I got sick and started puking. I felt like I never wanted to smoke again, but then I just smoked a blunt the next day and felt better.