I used to work with at least one person who would go to a grocery store, put a few cans of spray whip cream in the shopping cart, and take hits as he moved through the store, leaving the can when he was done wherever he could. He seemed to enjoy the high, although I did and do not condone such behavior. I have had nitrous oxide used on me many years ago by a dentist, and it did make me feel numb all over. However, he also gave me a shot of novocaine. I still felt a bit of pain as he worked. I could not imagine using only NO2 for anesthesia during abdominal surgery. Someone would probably need to lock me to a table, and I'd hope shock took care fo the rest.
I think I also saw the same movie on a plan. Must have had little marketing effort, because I had never heard of it.