We had this thread before but there wasn't a definitive answer.
How does anal sex Cause STD's?
Let's say Chad fucks stacey. Stacey has aids. Now Chad has Aids, than has anal sex with Becky. Now becky has Aids. But my question is how come the Intestines can block all the shit diseases but when someone sticks a cock in there it completely negates the Intestinal walls?
Also please forgive me for making such a Degenerate thread but IT IS IN THE NAME OF SCIENCE! So that makes it okay.