Scientific term used to refer to one who is a fat fucker. The first part of the word, "Endo", stems from the term "endomorphic", which refers to the body type that gains weight easily and tends to have a higher bone density and fat-muscle ratio. The second part, "sexual", is self-explanatory.
"Goddamn, Andrew, you are such a fucking endosexual!"
"Hippopotami are generally endosexual, that is, they are fat fuckers."