The first time I watched my wife do anal was with our regular bbc bull, she was lying back on a chair with her legs in the air, her plug in vibrator working her pussy and he was between her legs, from where I was sitting it looked like he was fingering her, so I just watched, her moans were getting more and more, so I moved over to enjoy a close up, I realised as I got next to them he was actually fucking her arse. Awesome sight, she still never lets me fuck her arse though