Well seems to be alot of people do these things, i generally see it when people are at a very young age, having sex outside in random places, bathrooms, public places where they assume no one knows, in baseball feilds/other sport type places.
and having sex with someone they met in the first night usually results in being in intoxicated.. but not always, i guess it just depends on someones life style, and how they respect themselves, and morals.
I don't find it weird at all because it happens all the time, normal? well yes i suppose so. but i do find some of it pretty disgusting.