What makes a sex scene legitimately sexy? Is it chemistry? Is it realism? Is it showing (more than a little) skin? Maybe it's the same thing that Supreme Court Justice Potter Stewart said about porn: You know it when you see it. (That said, the best sex on film is a world away from your average PornHub clip.)

In addition to the "this is hot" aspect, film has the potential to make sex subversive and to normalize certain acts and behaviors for a mainstream audience (if done right). On this list we don't only feature scenes that are interesting, wild, or sexy, but queer scenes (see the long, intense scene from 2013's Blue is the Warmest Color), uncomfortable and awkward scenes, and scenes that depict acts that people have often been ashamed of but shouldn't be. Ultimately, what these scenes all have in common though, is the ability to transform all sorts of sexual acts into something we can all consider for ourselves or at least feel differently about—all done in a tasteful way.

Rather than attempt to define what makes a sex scene successful, the Complex Pop Culture team rounded up 40 sensuous moments and explored what makes each tick. At face value, they have little in common, other than actors doing their best to fake an orgasm (and sometimes not even that), but each is titillating in its own way. From foreign cinema classics to indie films to mass-market sensations, these are the sexiest sex scenes ever to grace the silver screen.