We can't be even sure they have a gender, or if they're human? Are they smooth down there, like G.I. Joe? Or do they have several genders, like Species 8472?
BTW, Maru & Moro prove Rules 34 & 35 wrong. There's no Japanese fanart/doujinshi hentai pics of them (and terrible Paints/shoops don't count!). Ergo...