I'll admit our fun with our friend is why my wife took it in her butt. She has to be really turned on to try anal, when he's with us she gets really turned on so anal happens. She grunts instead of moans when he's in her butt and its sexy as hell.
When they do it she gets on all fours, he puts a lot of lube on and slides in really slow. Sometimes it's a few slow pumps, sometimes he gets going pretty good and cums back there. It's damn hit to watch.