Pussy. Basically anal anything is unnecessary higher-risk. I don't see a need to harm the woman I am romancing. Also, just looking at the disgruntled faces in porn it becomes clear (and a couple studies verify it) that most women do not enjoy anal sex (but some fake it, and a minority actually enjoy it). Nevertheless, if experiementation is to be done, I suggest omit "rimming" and "fisting" totally. IMO, the latter two have no place in the sensible realm of sexuality whatsoever.