Beautiful Princess, on the remote chance that you would ever actually want me deep inside your ass, please wait until I arrive to tell me. If I were to get such a text on my way to see you, I would either have a wreck or get a speeding ticket for sure!
(And BTW, your current avatar has probably already caused more boners than every Playboy centerfold ever published.

)
Regarding the original question, I don't know about body language, but whenever I've heard "Do anything you want to me," I've always translated that to "Fuck me in the ass," and I have never been corrected on that translation.