Your eyes squint. Your cheeks contort. The O face can be so odd that The League once dubbed the phenomenon “Vinegar Strokes”—as in, what you’d look like if someone put a spoonful of vinegar in front of your nose.
So why does it happen?
Unfortunately, there isn’t a ton of hard science on the O face. But that’s for good reason: The very people who study sexual behavior for a living can’t really observe you while you’re doing the deed, says Nicole Prause, Ph.D., a sex researcher at UCLA.
Imagine having scientists looking you in the eye, reading your hormone levels and heart rate as you come. Talk about killing the mood.
But in 2011, Spanish scientists found a way around it. They analyzed 100 videos of people’s faces during orgasm. (Men and women voluntarily uploaded these clips to a website.)
As the people climaxed, they commonly made these facial expressions:
• 92 percent closed their eyes
• 67 percent dropped their jaws
• 48 percent frowned or lowered their brows
• 44 percent parted their lips
The most common duo was a jaw drop and closed eyes, which happened when 36 percent of people came. Researchers speculate that some of these expressions are like reflexes—a release of muscular tension as you approach orgasm.
That’s why you look so strange when you actually come: You have zero control over your facial muscles in that moment.
In fact, some of these O faces more closely resembled expressions of pain than pleasure.
The reason: Many of the brain regions that light up when you’re in pain are also stimulated when you’re highly aroused, Prause says.
Sure, it’s not the most attractive look to cap off sex, but hopefully your partner is sporting a similar expression right along with you. And there’s nothing sexier than that.