My “handle” on a certain site is “Lord of the 2nd Ring.” I have been asked to explain "the second ring"
So here we go: the anus is the first ring – your butt hole. Then, deeper inside is the sphincter between the rectum and the sigmoid colon (large intestine) that is the second ring.
If the top's cock is long enough and the position is right, and the bottom is willing, you get to have two fucks at the same time. For the top, they are getting the head and top of the shaft fucked by the second ring and the main shaft fucked by the anus.
It takes a really good bottom to accept this and work his muscles to please the top but the bottom also gets the double pleasure of being fucked in two places at the same time. It often results in the bottom having a very powerful internal orgasm.
I am versatile so I know this from personal experience. And of course when those internal muscles start to squeeze down in those orgasmic spurts I come like a fire-hose, often multiple times in a single fuck. Just makes me want to keep going and going. I know this from personal experience as I am versatile and my husband can reach my second ring as well.