Hum, on 24 March 2012 - 16:26, said:
Erections are also a psychological, mental response.
If I am not in the mood, or comfortable with the situation, I do not get erections.
And if I get angry, I gaurantee you no sex would happen.
If you were not in the mood, or comfortable with the situation, you would not 'pre-emptively' get an erection from the phychological excitement, but when your prostate is manually stimulated, then you would then be erect, whether you like it or not, or enjoying it or not, or are in a lot a pain. Regardless of this you would physically become erect because you do not need to be erect in advance before the actual penetration starts to become erect after the fact that you are already having sex