XL Hung Guys – this is about both the length, and girth of the penis. It also can refer to how the penis, hangs low when flaccid, due to its size. The term ‘Hung like a horse’ is a common slang term, to denote someone very well endowed. One can have a rather lengthy penis, but not thick, or wide, and still be considered to be hung. Typically though, XL Hung Guys means a guy with a huge very big monster size dick.