Alright, you ready for a weird one? =P
I'm usually not into futa, but I refuse to deny a decent bb idea its right on this board.
So this one has a futa girl with a massive, and I mean ungodly, unrealistically massive set of genitals on her in a pillory (also called stocks) getting busted by a lesser endowed futa.
She first jumps and lands hard, ass-first, on the pilloried futa's balls, then squeezes her legs together around them. It's quite short (only 3 pics), and I'd personally prefer F/M, but you take what you can get, eh?
She proceeds to penetrate her over the remaining pic, while still sitting on her balls, but I didn't include it because it didn't really have the right focus. Regardless, you can view it by clicking the pic again.
http://g.e-hentai.org/s/2b60523a0e/366482-73
http://g.e-hentai.org/s/640cb1f82b/366482-74?nl=1
http://g.e-hentai.org/s/56ed7343b4/366482-75?nl=1
Again, I know it's weird, but meh, perhaps it will inspire artists to do similar types of busts, as a girl busting with her ass is strangely erotic. No? Just me? Fine then >.<
Eitherhoo, enjoy.