I doubt if I have ever seen one who has not seen one - if you know what I mean. Humanoids are curious by nature, they have to see everything for once. Now, your thinking is that it is not allowed (for God knows what reasons), but you cant tell me you have no idea what it looks like, right?
I never said that. I've studied here in Europe. I've seen biology books, taken exams in school. And once a friend and I watched stuff like that on internet and tv.