You could argue that almost every part of a woman’s body becomes a sexual hotspot during foreplay. But there’s proof that her knees, of all places, are worthy of extra special consideration.

The 2,000-year-old Kama Sutra is an elaborate Hindu study of male and female erogenous zones, written in Sanskrit. In the ancient text—via a lengthy 2014 review in Advances in Sexual Medicine—the authors advise “pressing” and fondling your partner’s knees, but only when the moon is in its waxing gibbous phase.

Modern sex experts agree with the first part of that—not so much the moon stuff. “The back of the knees is a major erogenous zone for women because it contains so many nerve endings,” says Ava Cadell, a certified sex counselor and doctor of human sexuality.

The more nerve endings, the more sensation and—in most cases—sexual pleasure, suggests a 2013 study in the Journal of Sexual Medicine. The same study shows the clitoris, the orgasm epicentre for most women, is an extremely dense little button of nerve endings.

During foreplay, once kissing is in full swing and you’ve both shed a few layers, position your partner on her stomach and run your tongue slowly along the backs of her knees and thighs, Cadell recommends.

Experiment with kisses, licks, nibbles, and caresses, she says. “She’ll be impressed that you’ve found a new spot.”

You could also invite a little friend to join the party. “I’ve had female clients say they’ve had orgasms using a vibrator behind the knee,” Cadell says. (That falls into the category of having to see to believe, but ladies, feel free to comment if you can confirm this phenomenon.)

But as always, the level of pleasure depends on the person. After sex, ask her to rate on a scale from 1 to 10 how much she enjoyed your new moves, Cadell recommends. If you get an unenthusiastic “6” coupled with a meh face, knee play may just not be a hot spot for your partner.