As I know in those situation the question is not about what you want to do buy more about what you can do :) so we should start with what are your capabilities.

It was hard to even tell what is going on in that animation what is that skiey thing but I think the most logical and erotic scenario woud be that he maybe he punches her with fist right to her ass, then his fist goes inside he lifts her on his fist belly bulges considerably until it explodes spilling all guts and blood. then he opens his fist grabs those intestines and pulls then back making them come out of her ass.

This is pretty easy to do in 3d and also looks good to me.