and I decide to check his browser history. There, I find a link to a porn site. Being the red blooded highly-sexed male I am, I click on the bad boy. It's a video of a woman being shagged by a horse. I check some more of his browser history. Here I find more videos of women shagging:

A bear
A dog
A tiger (!!?!?)
A donkey
Another horse
A monkey

How exactly do I stop being friends with the guy without mentioning my find? Do I stop being friends with him at all? Do I offer to help him sort his head out?

The thing is, outwardly he's an attractive, fairly well off guy with a steady job and good prospects. I guess you really never can tell about people.