Why is the prostate mentioned so often during discussions of anal sex?
The prostate is about the size of a walnut in a normal man, and is immediately behind the rectal wall about three centimeters inside the anus. It can be felt by placing one finger within the anus and feeling along the anterior wall for a round bulb. For some men, touching or rubbing this spot is extremely pleasurable; a rare few can even orgasm through this technique. Others report that the touch is painful or makes them feel as if they need to urinate. The alt.sex FAQ on anal sex answers this question in more detail.
