None wants to help you get a backstory (LOL) so you can fantasise about it. Go molest a homeless or some shit.
There's actually a large community of men who find that sort of thing sexually-appealing. It really wouldn't be that hard to find similar images. Backstory? Man vs Wild. BTW: I love your avatar, @patchiman.
I can only guess but it appears to be a bear (large and hairy homosexuals) being fucked in the ass while taking a picture of his.. Sodomizer? And someone appears to have taken the picture and put a caption on it.