I guess you can say they're HIV positive.

Clearly

I thought in the books his penis gets flayed not cut off.

Oh good god I hope not. It's one thing to flay his fingers. It's another to cut off his dick.
BUT JESUS CHRIST A FLAYED DICK. Can you even imagine?

Okay, I found out they flayed it then chopped it off.

Well that makes sense, that usually happens. But...SWEET MOSES A FLAYED DICK.

Its only implied as I recall, same in the books.

In the show it is only implied, but so heavily implied that it's undoubtedly true.
Example: The entire scene with the sausage in that gif.

True, but still only implied. Whereas poor varys explained the entire story of his... whats the verb form of eunuch? Eunuchification? No that just sounds retarded...

Anyways, Varys's penis fucking spoke to him.

Yes, but Theon's father and sister saw his in a box. What else could it possibly be? Implied yes, (thankfully, I didn't want to see the dick cut off, I had enough of that in "Teeth") but implied to the point where it's off for certain.

his finger that got cut off.

No.
Why would his finger be "his favorite toy"?
Why would Ramsay be eating the sausage in mockery of his penis, if it was his finger? - Again, gif.
Why would Ramsay talk about a "phantom cock" if he had only cut off his dick?
Why would the camera focus on Theon's crotch at the mention of that?

Seriously dude, the list goes on. His cock is gone forever.

Well, in my defense I hadn't seen the finale yet.

Ah. Well terribly sorry if I spoiled anything (however small.) I assumed you had seen it because of the comments.

Nah you didn't that scene with the sausage was fucking hilarious though. In a really a sad "Theon you're so pathetic" kind of way.

The thing is, Ramsay is so damn hilarious I don't find myself caring about Theon at all. In the books I care, but I can't tell if Ramsay being funny is a good thing or not. Either way I love it.