The word "Penis"

[Sethomas]

To me, the problem with the word "penis" is that it sounds like it's referring to the quiddity of pea. Hence, someday I must become a medieval philosophy teacher so that I can tell any number of jokes I have in store for the lesson to distinguish between quiddity and haecity.

"Phallus"?
"Noble organ"?

Your comment about the tail etymology being lame might be true, but not only is penis cognate of the Romance language modern words for penis, but also in German the word for "tail" is more often used as a vulgarized reference to the penis.