bad experience passing out

i'll try to keep it brief. but last night me and some buddies went out after a concert to smoke a joint. now, there were only three of us sharing this one j. we go out, we're having a good time and towards the end of the lifespan of the j, this dude sorta freezes up, goes limp, and won't respond to us. it's sorta like he's asleep, sorta like he's frozen, sorta like he passed out. but he can still hold up his own weight.

the posse, freaked out by what is happening tries everything to get him to respond. call his name, try to engage him in walking, letting him sit down, tapping him on the shoulder, etc. but this guy isn't budging. we check his pulse, he's alive, thank god. he's breathing, albeit lightly. finally, after about a good 3-4 minutes of this (which of course seemed like a lifetime) he opens his eyes, and is sorta able to respond. i say sorta because he doesn't really talk, sorta like he's just woken up and doesn't know where he's at. he grunts and shakes his head to questions we ask him, but that's it.

so we head out, back to our dorms, he's walking fine, we'll all trying to chat it up, not mentioning what just happened. but he starts to walk funny, swerving here and there, loosing his balance on turns. we actually end up running into security, but that's a whole nother story. by the end of the night, we get him in bed.

but my questions is: what the fuck happened?! he said (or his friend said, or someone brought up) that he may have been drinking earlier in the night. i don't mix alcohol and weed, but i know this kid who, when he was really drunk, smoked some and then got really sick. but like, vomitty sick, not unconscious sick.
i also think that it may have been his first/early experience with weed and his body just didn't know how to act. but if it was, i would've liked to think he would've said something. and even if he was inexperienced, would like, four or five hits do that to him?

all in all, it was a major buzzkill, but at least everyone/everythings okay. this ever happened to anyone before? know of people who this has happened to?