Several sources report that a study in the Journal of Clinical Psychiatry, titled "Shame and Guilt in the Aftermath of Sexual Attack" found that a vast majority — sometimes reported as 87% — experience an involuntary orgasm during the attack.
(Note: Many of the comments contain attitudes towards rape that many people may find disturbing.)
AutoAdmit forum thread, attributing the words to MSNBC:
A new study to be published in next month's Journal of Clinical Psychiatry is causing controversy in the psychiatric community for some of its unexpected findings. The study, titled "Shame and Guilt in the Aftermath of Sexual Attack", verifies much of what we know about the mental health of rape victims. However, one observation in particular is raising eyebrows. After analyzing the anonymous transcripts of over 5,000 post-rape counseling sessions, the authors point out that almost all female rape victims experience orgasm during the attack.
Asked for comment, Dr. Herschel Liebowitz, one of the authors of the study, said, "Millions of years of evolution has hard-wired women to be attracted to strong, dominant, and aggressive men. Unfortunately, rapists exhibit an extreme form of these characteristics, even if only temporarily, and this causes an unexpected and involuntary physiological response in the victim."
I find the claim to be hardly believable, as the nature of a rape is pretty disgusting. I'd like to know if that scientific article existed and was accurate.