The truly terrifying part isn't the teeth, although that should be enough.

No, the thing that manages to get me is that it seems to be a mouth. And seems to be functional.

Actually, on second thought, the size of the guy's balls is also of concern.

Man with four balls cannot walk.

Sheep nuts are a hassle

I am judging by your profile pic, but I am guessing you don't know how stupid balls are.

I mean, I look at that x-ray and I go "No wonder these guys look like they have a stick up their ass all the time! walking around with those humungous thing must be a constant, daily pain and endless source of discomfort, these guys probably have a tailor in common that accomodates it all".

I mean, it sounds funny and "big balls" have become metaphorical but I'm being serious here. The paragraph above isn't sarcastic, I genuinely think that such an excessively sized testicles would be a genuine fountain of daily discomfort. Big balls is not a thing a (sane) man actually would want. Human balls actually have an evolutionary adaption not found in other primates where one testicle is slightly higher than the other, precisely so they don't knock against each other all the time.

This is of course assuming that there aren't other things in that downstairs area, considering the penis doubles as a mouth. There must be some weird system to transport food (potentially?) to the stomach, if that is what that thing does.

They're sheep men, they're used to it

Imagine handing pre-pubescent boys a book titled "how to feed your penis in your adult years".

XD Oooo, not awkward at all.