It's an interesting fantasy to paint such a fat ass green! Ladies with such an ass are especially good in the crawl position, a boner is assured. Except you have to have a decent length tool. If you don't have one, I recommend laying the lady on her back and fucking her with your hands on her thighs pressed up against her belly. Otherwise you can't get the dick in deep.
This brunette is very bright and liberated, and it's a pleasure to have sex with these kinds of girls. The fact that she has developed her anus like that and then moves it on her own at a brisk pace is rare at all. If she moans sweetly, it means that she gets a high from it, and not just does the job.