This legit situation happened about four years ago with me and three friends. I was driving back from Baltimore, and we all did our shots after stopping in a parking lot somewhere. My friend in the front seat had a bit of a lower tolerance than the rest of us, but did the same amount as we did. After getting back onto the road, within maybe 3-5 minutes, he had increasing difficulty staying awake, with breathing, etc. He went completely out. I was on the highway and I had to keep driving, thinking they would be able to wake him up at any moment.
We all started screaming at him, we poured water over his head, the guy behind me starting twisting his nipples, smacking him, flicking him in the nuts(...), but nothing seemed to work. I asked if my friend in the backseat had his sub script with him and he did, and I said we should put it under his tongue. The guys in the backseat managed to place it in his mouth, we presume under his tongue although you can't say for certain. We held his head tilted back a bit, both opening his airway and preventing the suboxone from moving too much. After a moment he started to breathe, but with difficulty, and he went from full-on out to an extremely deep nod (His breathing started to regulate, however eradicate, but we could tell oxygen was now being exchanged) but he was still unconscious, sorta like sleeping. he stayed like this for about 20 minutes, slowing his breathing progressively regulated and he eventually came to and woke up, however he started getting ill. He was pissed that he was now extremely dopesick and kicked into withdrawals, and he was mad at us for the rest of the day. Go figure.