Malificence!!! 
I hope DP doesn't look through my internet history to find inspiration for my anniversary present now 
This will be my first... um... "outing" on a bumsex thread. 
I was always really adamantly against it. Said I would never try it. Couldn't understand why or how it could be at all pleasurable. But did enjoy some mild anal stimulation, which DP enjoyed as well, so he just kind of.. kept going. And then one day I was getting really into it and I told him I wanted to try anal sex. So we got set up with some pillows, I used a vibrator on my clit, and he went in, pretty much just that, and I had probably the most intense orgasm of my life in the next 3 seconds. I literally couldn't speak and my vision blacked out for 30 seconds or so. I was crying and laughing at the same time and he was SO worried in case he had hurt or upset me, and I couldn't get the words out to say it was fine, it was amazing, for about two or three minutes!
We've done it a few times since then and it's always just been the pressure for me (and vibrator combination ) - the one time he managed to stay in long enough to do any movement I found the moving made it just feel like vaguely uncomfortable, not-orgasmic doggy style. So completely pointless. And once we did it and I hadn't had the build up and was possibly a bit nervous and it hurt, a lot, and that put me off for ages. But in those rare sessions with lots of build up, when I've suggested it rather than DP, with a decent vibrator, and just the pressure rather than movement, the orgasms can be explosive. (I suspect I might have a problem if DP was too large as well, thankfully, he's not!)
And actually, bizarrely, I find it massively empowering. Which is probably just because it's the first thing I've ever actually suggested for myself, really wanted and been in control of, and enjoyed the first time I did it - for everything else I've always felt like I was doing it because that was what you did and it took me a while to get used to it.