I have passed out once from weed. I was at a concert and smoked this 1.5 gram joint while standing. I started to feel light headed and I started swaying and then nothing, I woke up on the floor a minute later with my buddies trying to wake me up. I felt fine afterwards. I think I passed out because I locked my knees. This happened 7 years ago, and I haven't had anything like that happen since...