I don't know how you can have never had an anal orgasm before! They're inescapable!!!! Ever since I was first penetrated, I have had an orgasm from being fucked. And, every guy I've ever fucked had an orgasm from me fucking them. When I'm fucked, his cock slides against my prostate, stimulates my rectum and when he thrusts deep, tickles my sigmoid colon. This is pure pleasure and is the best feeling ever.
In order of intensity: Prostate
Sigmoid colon
Rectum
The man's rectum IS a sex organ and is the equivalent of your knob (glans penis) on your penis. When I reach near orgasm, I notice that with each thrust inside me, my cock involuntarily twitches and spasms. As sensitivity increases, my toes curl and thighs tighten and twitch and I moan with each push. Eventually my balls feel like they're quivering and tightening and he thrusts; my balls throb, my cock twitches and cum drizzles out. He thrusts again; balls throb, cock twitches, cum drizzles out. This happens a few times and then I have an intense orgasm. My balls tighten and throb and cum squirts out all over him about 5 times (if he's on top) or at least half a meter in the air. While this happens, my anus tightens around his penis and he cums too, so our orgasms are almost always simultaneous. This doesn't mean I don't love a penile orgasm too, they can be just as intense and I love giving them to guys. When I fuck a guy, he does the same thing too; with each stroke, he cums. Sometimes just a little each time, sometimes it gushes out of him, so I go extra slow and deep to make him cum longer. I don't like to jerk off or touch myself during sex. I use the missionary position a lot so you can't anyway but when I'm in the spoon position or when I'm not facing him, in all positions, I explore his body, have my arms tightly wrapped around, stroking his hair, or holding his hand and connecting with him. The pleasure of his cock moving inside you is enough without stimulating your penis too. I also found once that if I try to rub my cock, I wouldn't cum, though I still had an orgasm but it was nowhere near as good.
If you want to make him cum, when you penetrate him, go in slowly and rotate your basin and take a good feel of his insides with your dick. Find his prostate and make sure you apply super pressure here during sex. Rotate your basin a lot and feel inside him. This will make his rectum feel great and if you have a long cock and he wants it, thrust deep into him and tickle his sigmoid colon. Use lots of foreplay to make him super horny and just connect with him well. Even if its just a one night stand, make an effort to really connect with the man you're having sex with, the man you're sharing your penis with and the man who's sharing his rectum with you.
Remember, the male rectum IS a sex organ
the lower bowel of a male IS a sex organ
The rectum is just as important as the penis and is just as important as his penis in his sex life