As far as I know, all the cloaca related images on this board come from Postbear
I think maybe the background you refer to is actually a horse vagina he shopped into a fractal design that some one on here thought was a cloaca at first.
www.b3ta.com/board/6113227
( ,
Sun 23 Jul 2006, 10:17,
archived)
www.b3ta.com/board/6113227