Here's the thing. People have sex. Movies have sex scenes. Wouldn't it be intriguing if a movie featured two actors having actual, consensual sex, instead of just mimicking sex in a way that looks great onscreen but is almost certainly very, very awkward in real life?

Try is the operative word. Gyllenhaal and Ledger saddle up to play gay cowboys whose relationship becomes official in a secluded tent after a night of too much whiskey. One of the most celebrated sex scenes of all time, this one is artfully done and told out of sequence—director Steven Soderbergh being as playful with editing and time and narrative as his two leads, Jennifer Lopez and George Clooney, are with each other. Flirty and cheeky as they undress, they do finally get horizontal, their lips do finally lock, and unfortunately, the screen does finally fade to black. In the Realm of the Senses has long been considered one of the most perverse and erotic films to have ever slinked across the screen. Sexually explicit and non-simulated in its acts, the art-house gem about a real-life tabloid scandal features countless coital climaxes between its two leads.

Sex scenes are nearly as old as movies themselves. In fact, one of the first films to be screened for the public debuted in and was called The Kiss. It was quite steamy for its time, featuring a full-on brushing of the lips, which, let us tell you, really riled up the modest-minded folks of the late 19th century. These days, a sex scene has to shock for us to consider it among the greatest sex scenes of all time. It has to make us laugh riotously, recoil in disgust, squirm at the weirdness, or at the very least, rewatch it repeatedly because it's just so damn hot.

Both mainstream and art house cinema continues to blur the line of what is acceptable to show on screen. Forgetting that Blue is the Warmest Color opens with a ten-minute sex scene, the actresses draw attention during a heightened six-minute scene when they are shown actually masturbating to help create arousal in the moments building up to sex. The anatomy may have been prosthetic, but the actions performed were nothing short of authentic. You create the controversial 70s classic Caligula. A sex-obsessed Roman emperor Malcolm McDowell puts on a show as graphic as the fantastical orgies in ancient frescoes.