Wasn't this question answered in "When Harry Met Sally"? The real question is why?
Dr. John Grohol over at PsychCentral published this article yesterday: Why Women (And Men!) Fake Orgasm? The results of a study done at the University of Kansas (my alma mater) aren't exactly surprising:
The researchers found that the responses suggested a sexual “script”
that most of us follow, or would like to follow. Boy meets girl, girl
takes boy to bed, girl has an orgasm before the boy. And the boy [has an orgasm] in
response to the girl’s orgasm (although not as much, vice-a-versa).
Faking an orgasm is a predictable response to this set of expectations,
to ensure the “script” goes as smoothly as possible.
that most of us follow, or would like to follow. Boy meets girl, girl
takes boy to bed, girl has an orgasm before the boy. And the boy [has an orgasm] in
response to the girl’s orgasm (although not as much, vice-a-versa).
Faking an orgasm is a predictable response to this set of expectations,
to ensure the “script” goes as smoothly as possible.
Read the article. And then enjoy the video. It's a hoot.
The older woman at the end of the clip is the director, Rob Reiner's mother, Carl Reiner's wife, Estelle. She practically steals the scene in less than two seconds.