"Bringing this type of shame to a man can be exceptionally devastating to their emotional self conscience. By not being able to fend off an attackers the victim may view himself as weak, undesirable, or even homosexual.
These feelings of homosexuality can be even more confusing if the victim experiences an erection or even ejaculates. Both of these situations are very common and are often used as tools of shame by an attacker to make the victim think that they wanted or enjoyed being raped. In reality these types of reactions are more physiological than anything.
Often people believe that an erection equals sexual arousal. There are many reasons why a man may experience an erection during a sexual a**ault. The simple friction of touching the millions of tiny nerve endings on the penis could cause an erection, even if the touch was unwanted or unpleasant.
Being penetrated anally can also cause an involuntary erection. The application of pressure on to the prostate gland from digital, penile, or foreign object insertion to the anus can often cause an erection. Any proctologist will tell you that this type of reaction is very typical while performing a Digital Rectal Exam for prostate screening.
Bringing the victim to the point of ejaculation is also quite common. Rapists will often make every effort possible to ensure that the victim does ejaculate to add the the feelings of guilt, shame, and homosexuality. This can add another layer of power, and dominance, and even increased pleasure for the rapist for having such control over the other person. Remember in most cases its about power not the actual sex."
http://www.theforensicnurse.com/content/index.php/tag/rape-statistics/
