We've done it. It's hard. The guy behind has to go easy. In up to the balls is good but wife has to set the rhythm. I'm sure she likes it but she really likes to kiss one of us while other is doing her. I'm good with in her mouth while he's doing her from behind, it's a nice view.
We don't get very wild we like to take turns with her, him and I like to watch, she likes us watching. There's plenty of hard fast fucking but we like slow sensual lovemaking type sex too.
The huge kink for her is the other guy going right after first guy finishes. She gets really turned on, us guys get turned on, we each do her at least twice.