Sleeping Gas

When I was really little, I had to go to the hospital a couple of times to have a laser treatment on a birthmark. I always thought the treatment was to remove the birthmark and that it failed because because my birthmark is still there (and it's pretty large). However, I was told later in life that the procedures were simply to reduce the severity of the mark. If I had not gotten the treatment, the birthmark could have become thick, puffy, and maybe even hard. I imagine it would appear something like rhino skin, but I honestly have no idea. All I know is, the mark is still on my neck and it's very apparent. It feels like normal skin, so I forget it's there. But sometimes I remember its there when people ask if I have a rash or something. Surprisingly many people just assume I had been burned at some point in my life. I have to reassure them that that's not the case, even though it's kind of a cool story.
Anyway, I remember going to the hospital when I was really little. They told me they were going to use lasers on my birthmark, which I thought sounded awesome. I was excited to see some lasers! But I had to be asleep when they did it, so my hopes were vaporized.
I still have no idea what exactly they did during the procedure. What I do remember is walking down a long glass hall with a giant machine in the wall. It was some sort of cool instillation for people to look at as they make their way through the building. The intricate parts and pieces made it look like the inner workings of a giant watch or clock. Things moving and clicking, cogs turning, etc.
I had to wear pajamas for some reason while I was there. Maybe because they were the most comfortable clothing option for me. They also gave me these thick socks with small pegs on the bottom that were kind of like cleats (but not, obviously). They felt weird on my feet and I never knew why I had to wear them.
Things are blurry from that point forward, but the one thing I always remember is laying on a sort of operating table and having the gas mask put on me. A nurse would ask what "flavor" of the gas I would like and I always went with bubble gum. The flavored air tasted pretty good! As the gas made it's way into my lungs, they told me to count backwards from 50 (or whatever number they had specified). It never took long before I lost count and passed out.
It's a shame that I don't remember the procedure itself. I would have loved to see some lasers. We went back a couple more times in order to fully take care of the birthmark. I don't remember each in particular event. They all kind of blend together in my head.