I've done the getting a massage while wearing a diaper. I wore a Super Dry Kids diaper. The Pampers replica. It was awesome.
I went to many sort of shady massage parlors, and most didn't even care. No diaper change for me.
Then I found one that really got into it. They were asian, and said "no poop" in limited English. I was more than happy to oblige, but I did wet my diaper on purpose.
Before all this, I remember the madam of the parlor taking my money, I was instructed to go to a room, and remove my clothes. I did except for my diaper, and had my diaper bag.
They girl that nassaged me giggled a little, and said "big baby".
I got an excellent massage with a happy ending in my diaper, and was changed. It was a simple as that. I tipped 40 dollars, and she told me to come back soon again.
It took me a while to find the right place, but I found it.
They were closed down a couple of months later. How sad.