The area between the sack (or twat) and sphincter, as minspronounced by my mildly-retarded friend, Mark, who didn't realize the correct word is "taint".
Mark told us his wife tongued his "tate" last night. We had no idea what he was talking about, then he said, "you know, the skin between your balls and asshole." We cracked up, not believing how a 35-year-old retard like him could possibly hold a full-time job as an English teacher and not know that "taint" is the correct terminology. He is now known by us as "Larry Tate".