How to approach my BF about playing with his ass?

[satindesire]

just because YOU orgasm massively during anal sex don't expect that to happen if you use a strap-on on him. The plumbing just ain't the same.

During anal sex he is poking your A-Spot (probably) and that will cause the massive O's. Poking a prostate does not produce orgasms. It can enhance an orgasm from a hand job or a BJ but the thrill for either or both of you is the roll reversal if you get to fuck him there.

I hope you understand that "poking a prostate" can cause orgasms in some men.

The "plumbing" may not be similar, but some people can orgasm just from KISSING or thinking about sex. Discounting it as impossible isn't a wise course of advice, my friend.