I take a little more indirect approach. When are playing sexually or talking immediately after a wonderful, mutually satisfying lovemaking session, I’ll ask them if I can ask them a personal question. If they say yes, I’ll build their curiosity by asking, Are you sure, you promise I can ask something personal, etc.
After they have reassured me repeatedly and sound a little annoyed that I continue ask for reassurance, I’ll ask if they have any secret fetishes or practices they enjoy.
This will bring out somethings because their defenses are down after a thorough fucking. If our screw included anal play or even anal sex, they will usually mention enjoying anal play. At that point, I feel comfortable to admitting I enjoy enemas, how good they make me feel and it’s better when or if a friend helps me. 99% of the time, we bring out the equipment at least for a show and tell or an enema exchange begins.
If they don’t mention any anal erotism, I make up a story about getting frequent enemas as a child and learning to enjoy them and finding them sexually stimulating as I got older. I never had any partner not understand why.
Usually they will share their own childhood enema experiences and say they have had lingering thoughts about including them in their sex activities or even their medfed play.
Either way, I know if it’s safe to discuss further or not without being considered weird or kinky.