It has long been known that women can be guilty of faking the throes of passion in the bedroom, but a surprising number of men feign orgasms too, according to research carried out by a Harvard academic.
In his new book 'Why Men Fake it: The Totally Unexpected Truth', clinical professor of urology Dr Abraham Morgentaler, recounts numerous stories of men confessing that they pretend to climax.
But the biggest shock was their reasoning.
'The big surprise to me when I started doing this work 25 years ago is that once a man is in a relationship, he seems to care more about his partner than himself,' said Dr Morgentaler.
'For every man who behaves badly, I can give you 10 who are dedicated and thoughtful and doing the best they know how to be a man and a solid partner.'
It may seem unbelievable - not to mention physically impossible - but it is indeed possible for men to fake an orgasm, although quite how they do this is kept under wraps by Dr Morgentaler in an interview for online magazine Salon.
Dr Morgentaler's book paints a picture of a gender who are anxious about their erections, feel pressured into having sex and are concerned about their partner's pleasure.
A recent study from the University of Kansas found that 70 per cent of women and 30 per cent of men admitted faking orgasms.
In the study, both sexes gave the same reasons for pretending - a partner's orgasm was imminent so they felt under pressure to climax.
The report said: 'The emphasis on men's ability to give their partners "earth-shaking orgasms" sometimes leads both women and men to pretend orgasm to meet these expectations.'
Dr Morgentaler says another reason for the rise in faked orgasms is down to the rapid change in gender identity across society, which has led many men to suffer a crisis of confidence about their masculinity.
He cites the case of a 27-year-old paraplegic who can't feel or move anything from the waist down.
'I treat him so that he can have sex, and he comes back and is totally thrilled. His whole personality is different. He says, “It's fantastic. I feel like a man again!” But here's the thing: He feels nothing down there.'
Dr Morgentaler explains that the patient feels good about himself as a man - not because he's getting pleasurable sensations from sex, but because he is able to satisfy his wife.
He adds that until around 60 years ago, having sex was understood as a women's duty rather than something she should enjoy. But now women expect to be pleasured.
He illustrates his point with a patient who suffered with erectile dysfunction and was concerned he would never be able to find a partner because, he said, 'What woman would want to be with a guy that can't satisfy her?'