The new monsters of cock vid with Jack Napier and Diana Prince is a must see on this topic. Jack goes balls deep in skinny Diana who can't shut up about how far up in her belly she feels him. Finally Jack stops the action to show us where exactly in her tummy he is. They mess around making belly bumps just to drive home the point. When she points at her belly button moving, she says it's like a baby kicking. Jack asks her permission to really "hit it" and she tells him to go for it. She gets a no prisoners pounding that leaves an impression.
I didn't find any free streaming links. BangBros is still trying to monetize the scene and it's worth the $.