I have always been very anally inclined and have not only enjoyed anal sex with girlfriends, but alot of self anal pleasure with dildos, plugs, enemas, etc.
 
Before I got married, my last girlfriend was pretty adventurous, and we enjoyed anal sex quite often.  I had been fantasizing about her fucking my ass with a large strap on for quite some time, so I bought her a harness and a thick nine incher to go with it.
 
One night after fucking her in the ass, I asked if she would like to turn the tables and I presented her with the harness and dildo.  She strapped it on and looked incredible(36Ctits, long brown waist length hair, and a nine inch "cock").  She put me on my hands and knees and buried her face in my ass(I love having my asshole licked).  Then she took a jar of anal lube and slid a greased finger up my ass.  My cock was so hard that it was dripping.  She added a second finger and then a third before pulling out.  I looked over my shoulder and she had the nastiest look on her face as she greased the dildo.  I reached back and spread my cheeks wide for her and I felt the head against my asshole. She grabbed my hips and shoved her entire cock up my ass in one incredible thrust.  I cried out and she just started fucking me with long hard strokes(pulling almost all the way out, before thrusting back in).  She must have fucked me hard for a solid 20 minutes or so, spanking my ass as she did.  I came twice during that session and I can still picture her long hair whipping around as she fucked me.
 
I bought my wife a strap on a few months ago but she has only used it on me twice.  I am so excited now though, that I think tonight should be the night for another incredible session.