In W_hen Harry Met Sally_, Meg Ryan famously quipped that "most women at one time or another have faked it." The "it" she was referring to was, of course, the female orgasm.

And she was right. Study after study has shown that the majority of women say they have indeed done it before—but it's not just women who fake orgasms. Recent research has found that, at least among college students, about 1 in 4 guys say they've done it, too.

So why are so many women and men pretending to get off? A new set of studies published in the Archives of Sexual Behavior aimed to provide the definitive answer, and the results suggest six distinct themes.

In the first study, researchers surveyed 50 college students who had faked an orgasm before, meaning they didn't have an actual orgasm but either acted like they did or told their partner they did. They were asked to reflect on their own experiences and generate a list of possible reasons that someone might pretend to climax during sex. The researchers took the resulting list and added in dozens more possible reasons drawn from other research on what motivates sexual behavior more broadly, just in case the students hadn't thought of something.

They then conducted two follow-up studies that, combined, involved more than 1,400 adults (mostly recruited through Craigslist) who also had prior experience faking orgasms. People rated their agreement/disagreement with each reason on the list, and the researchers then looked for patterns in their responses.

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Their analyses revealed that people's reasons for faking orgasms clustered into six distinct groups:

1.) It feels good ("it is exciting and satisfying," "it makes me feel loved").

2.) It's something I do for my partner ("I do not want to hurt my partner's feelings," "it makes my partner happy," "it increases my partner's arousal").

3.) I'm not into the sex ("sex is taking too long and I want it to be finished," "sex is not enjoyable").

4.) I want to manipulate my partner or feel powerful ("I enjoy exerting dominance and control over my partner," "it is a powerful tool I can use to get other things I want from my partner").

5.) I'm insecure ("I don't want my partner to think I am a bad sex partner," "I am afraid my partner will get angry with me if I don't").

6.) I want to emotionally connect with my partner ("it is a way to express love," "it makes me feel emotionally close to my partner").

As these themes reveal, people sometimes fake orgasms for themselves because they're getting something out of it. Other times, however, people fake it for the sake of their relationship because their partner gets something out of it. And yet other times, people fake it because the sexual circumstances just aren't going to produce a real orgasm.

This new research found that, consistent with previous studies, more women than men said they had faked an orgasm before. But not only do women fake it more often, there are gender differences in reasons for faking. Specifically, women were more likely to have pretended to orgasm for the benefit of a partner, whereas men were more likely to have pretended orgasm due to feelings of insecurity, a desire to emotionally connect, and because they wanted to feel powerful.

Our reasons for faking also vary with age: Older adults are more likely to pretend orgasm because they want to please their partners and emotionally connect with them.

So is it okay to fake an orgasm? There's no simple answer here. Pretending to orgasm isn't inherently good or bad—it really depends on your reason for doing it. What this means is that you shouldn't necessarily assume that a fake orgasm here or there is a red flag. Indeed, as the authors of this research wrote in their paper, "pretending [to have] an orgasm is not by itself an indication that the couple has issues to resolve."

That said, if you're doing it because the sex is bad and you're going to keep having sex with this person, faking might not be the best idea. All of your moans and groans might give them the wrong impression about what gets you off, thereby setting the stage for even more disappointing future encounters. You're probably better off communicating with your partner about what feels good and what doesn't.

Likewise, if you're doing it because you feel that an orgasm is expected, you're just feeding the orgasmic imperative, or the idea that sex isn't really sex without orgasm—and that's just going to amp up the performance pressure on you next time around, thereby reducing the likelihood that you'll have a real orgasm.

By contrast, if you're faking it because it's something you thoroughly enjoy or because you truly want to make your partner happy, that's another story. In this case, all of those pretend moans and groans could potentially improve the sex, and maybe even the relationship, too.

Justin Lehmiller is the director of the social psychology program at Ball State University, a faculty affiliate of The Kinsey Institute, and author of the blog Sex and Psychology. Follow him on Twitter @JustinLehmiller__.