Rectum
From BeastWiki
Rectum is the final portion of the large intestines in mammals and gut in other animals. It reaches to the external opening called the anus.
[edit] Sexual stimulation
Sexual stimulation of the rectum and rectal muscles is sometimes practiced by people. In females, the rectal muscles is located near the vagina and they share some sensitive nerves. In males, the prostate also shares a number of nerves with the rectum and stimulation and penetration of rectum can cause sexual arousal.
