Another thing science has given us for buttholes? Biological evidence of why some men love to bottom — hallelujah. The same muscles you use to hold farts in are the same that help you spunk. The kegels or pelvic floor muscles are found by trying to stop peeing mid stream or just by tightening the muscles that keep you from passing gas. Just like any muscle, doing kegel exercises can make them stronger.

In humans , the anus from Latin anus meaning "ring", "circle" [1] [2] is the external opening of the rectum , located inside the intergluteal cleft and separated from the genitals by the perineum. Two sphincters control the exit of feces from the body during an act of defecation , which is the primary function of the anus. These are the internal anal sphincter and the external anal sphincter , which are circular muscles that normally maintain constriction of the orifice and which relaxes as required by normal physiological functioning. The inner sphincter is involuntary and the outer is voluntary.

The human body is an amazing thing. For each one of us, it's the most intimate object we know. And yet most of us don't know enough about it: its features, functions, quirks, and mysteries.