I did it once (around 2008) to "prep" myself for a holiday in the sun. My mum said I was looking a bit pale due to my mostly nocturnal lifestyle at the time and suggested it.
I thought, why not? Build a base tan, as they say.
I walked backwards and forwards in front of the tanning salon for a while, to make sure nobody I knew saw me go in there, and quickly dived through the door. I sheepishly asked for a suntan and the woman behind the counter let me buy enough tokens for a stand up one for like 6 minutes, maybe 9, I can't quite remember, but it wasn't a long time at all. I kept my boxers on, as much as an experiment to see if there was a difference in skin tone than anything else.
It was an absolutely dreadful idea. Six hours later I was lying in bed with cold damp towels on me, I could barely move.
A week later my girlfriend, now wife, was peeling thick homogenous sheets of skin off my legs the size of A4 paper. I'll always remember the sound as it came off. Scchhhllliiiiiiick. She's a picker, so she loved it.
So, my advice is: don't do it. It hurts, it stinks (you can actually smell people's skin burning (
link), the whole place smelled of burnt, dead skin cells), it's unsanitary (by all accounts these places are generally grubby) and gives you cancer.
I could probably have reported the salon for letting me go that long. I was obviously pasty and white and didn't have a clue what I was doing. But I chalked it up to a lesson learnt and tried to forget about it. Thanks for reminding me.