The word Tailenis was originally formualted to explain a tail / penis like appendage on a small soft toy bear. It describes something which could be viewed as either a penis or a tail, but is ultimately indeterminable.
Tailenis can also be used as an insult towards men who act stupid, sleazy, creepy or in a caveman manner, to explain that they have not evolved and are an evolutionary throwback.
"Ya know what, I think I'm going to leave his unusual manhood alone, partly because I think it adds character, and partly because its inhumane to cut a tailenis off anyone."
"Leave me alone, you creepy tailenis"