More directly, 18 is not the moment you take the shrink-wrap off your genitals. It's when you get thrown to the wolves. It's the point where you're assumed to already know enough that all your future decisions are your own fault.

Drives me up the wall when fandoms are like 'You can't show that seventeen-year-old having impure thoughts about a close friend! It's still six months until they can get facefucked on camera for money.' If y'all can't handle that for fictional characters, the unrefined horniness of actual pubescent humans is going to obliterate your psyche.