Being a nurse and having to care for babies with colostomies, I had to jump in here. I consider myself open-minded but, I would strongly caution against trying to penetrate a colostomy. Have you seen a colostomy? Do you realize that a small portion of the dissected bowel is actually brought outside the body? The actual diameter of the interior of the bowel is quite small (even in adults), and as Jack Rabbit said, there is no muscle that would stretch like the anus. Any manipulation of the stoma can cause bleeding, and excessive manipulation/friction can cause the stoma to prolapse or basically extend further outside of the body.