Stretching her asshole open, priming the pump with plenty of lube and watch her lean back as her ass cheeks spread apart and that tight butt-hole begins to gape.
Men fuck women up the ass, women put on strap-ons and peg their men, and anyone can fuck their own butthole.
Come for the porn but stay for the sexperience! Once it's all over, a deep enema is the only way to make sure the asshole is clean and ready for more ass fucking.
Anal porn always focuses on penetrating asshole.