A fake orgasm occurs when a person pretends to have an orgasm without actually experiencing one. It usually involves simulating or acting out behaviors typically associated with orgasm, such as body movements, vocal sounds, and sequences of intensification followed by apparent release. It can also include giving verbal indications that orgasm occurred.

While all genders fake orgasms, women fake orgasms more frequently than men. A survey of 180 male and 101 female college students (introductory psychology students from the University of Kansas), Muehlenhard & Shippee (2009) found that 25% of men and 50% of women had pretended to orgasm (28% and 67%, respectively, for participants with experience in penile–vaginal intercourse (PVI)). Although most fake orgasms occurred during PVI, some participants also reported them during oral sex, manual sex, and phone sex. The ABC News 2004 "American Sex Survey", a random-sample telephone poll of 1,501 Americans, showed that 48% of women and 11% of men faked orgasms. A 2012 joint survey of men's lifestyle site AskMen and women's lifestyle site TresSugar (now PopSugar) found that 34% of men and 54% of women had at some point faked an orgasm; 26% of women said they faked an orgasm every time they had sex. Other studies have found that anywhere from 25 to 74% of women admit to faking an orgasm at some point in their lives. This is more than the 25 percent of women who, according to Psychology Today in 2010, reported consistently having an orgasm during coitus. Women tend to achieve orgasm during intercourse less readily than men because most women require direct clitoral stimulation to achieve orgasm, and not all sexual positions provide access to the clitoris, which can make orgasms difficult to achieve for women. For women in heterosexual relationships, faking an orgasm can also be rooted in deference to their partner, need for their approval, or feelings of shame or sexual inadequacy. As there appears to be 'a sexual script in which women should orgasm before men, and men are responsible for women's orgasms', a woman may feel pressured to fake an orgasm before her partner in order to please them and avoid hurting their feelings.

Men fake orgasms for several reasons. Some fail to orgasm, but fake climax in order to avoid hurting their partner’s feelings. Also, some men may wish to end intercourse, but believe that sex must necessarily end with a man orgasming, and so fake an orgasm to fulfill that. For men, it is more difficult to fake an orgasm, since ejaculation usually accompanies orgasm in males, and their partners can usually see whether or not this happens. Faking orgasms in men becomes easier while using condoms. In rare cases, a man is worried that the condom is torn or will tear, and that he will unintentionally make his partner pregnant, and so he fakes an orgasm in order to avoid ejaculation.

In a 2005 University of Groningen study conducted by Gert Holstege and Janniko R. Georgiadis, the brain activity of 24 men and women (12 couples) was observed in an MRI scanner in different circumstances. For the female participants, their brain was scanned in four states: simply resting, faking an orgasm, having their clitoris stimulated by their male partner's fingers, and clitoral stimulation to the point of orgasm. Brain scans found that, when women were tasked to fake an orgasm, the female brain centres that control conscious movement remained active, whereas when they experienced real orgasms, all activity disappeared from the movement control centres, and the light from the emotional centres of the brain went out as well. With the exception of some Brodmann areas of the cerebral cortex (which only showed activation in men), the same brain regions were activated or shut down in men and women during real orgasms (although the female orgasm was found to be longer and more intense on average).

According to a PET study by Huynh et al. (2013) the dorsolateral (left) side of the pontine tegmentum area was always activated whenever women had a real orgasm, attempted but failed to have an orgasm, and imitated (faked) an orgasm, whereas the ventrolateral (right) side of the pontine tegmentum was only activated when women had a real orgasm.

Orgasm is not always achieved easily during sexual activity. For both sexes, the condition of being unable to orgasm during sex is known as anorgasmia; it can be caused by a variety of factors, including factors in one's life such as stress, anxiety, depression, or fatigue, as well as factors related to the sex itself; including worry, guilt, fear of painful intercourse, fear of pregnancy, the undesirability of a partner, and the undesirability of a setting. It can also be caused by drug use, including alcohol and other substances, or side effects from prescription drugs.

People can fake orgasms for number of reasons, such as when their partner wants them to orgasm but they are unable, or when they desire to stop having sex but are not comfortable telling their partner directly, avoiding negative consequences, or for pleasing their partner.

That women should fake an orgasm was, about the year AD 2, recommended by the Roman poet Ovid in his famous book Ars Amatoria: