Nirgilis

You don't get major chemical burns from watered down alcohol, so what kind of other stuff is involved?

Don't worry about that shit. I was 18 too.

Regarding masturbation, if you really get it going, are there odds you might break your arm or hand? I suppose that'd be very awkward.

Yeah, that's what makes it so improbable. I work with 70% ethanol daily, and 99.9% when making scales to measure against. It touched my arms dozens of times and while it feels pretty cold and irritates slightly, it not a problem at all.