^ I have a buddy who actually went perma-crazy back in the late 90s, after inhaling two separate "Reddi Whip" whipped cream bottles of their gas, without taking a breath of air in between. He held the last one in for like 30 seconds and then passed out.
His personality drastically changed, after coming to. We thought he was joking around at first, we were like 12, but I still remember that crazy look in his eyes. He is OK now but needs meds. He is also very paranoid.
Just shows that even sober, some people are not compatible with NMDA antagonists, especially at such a young age.