When I first started smoking weed, the first couple weeks (I'd hit the pipe maybe 3-4 days out of the week) I would blackout a few times while I smoked. The blackout would occur while I held in my hit, and I'd keep doing this because I didn't exactly know if there was a limit or if I was high. I'd stop once I'd realize I was having a hard time keeping my balance, and after those couple of weeks the blackouts stopped and I figured I wasn't getting as high. So I'd hit more bowls until I felt like it was enough, but never blacked out again. So what I'm wondering is if it was the weed that was causing me to blackout, or the lack of oxygen to my brain while I held it in - my friends say they've never heard of anyone blacking out like me and said my stuff could've been laced.