This movie has no violence (although a kid threatens to kill another kid. We see them tackle and that's about it), no nothing else except a ton of swearing, and most of it comes from a kid (about maybe, 10? I have no idea).
However the unrated version has full frontal female nudity once, and a kid sees a woman's top half of her body (the rest of her is under some sheets), although since this is only for the unrated version, 15+ for the actual movie.
Another thing, is the talks about sex. Even in the rated version, you see a guy naked, face down on the ground, and a lot of talk about sex with a kid. One conversation is still drilled into my mind, about an adult and a young kid talking and "observing" woman's breasts.
Anyway, 15+ for a lot of swearing, but in the real world, you probably hear a lot of this kind of language a lot.