I have also had this fantasy and told my husband .
When it happened I was not aroused .it was in the middle of the night . I was in deep sleep when I felt my anus being massaged. But what was actually happening was that he was lubricating me. I wanted to continue sleeping so I pretended to be asleep. When I felt my checks being spread and felt something being inserted I still did not realize that is was a nozzle, I thought it was sex toy! Then I heard the clamp release and felt the warm water flowing into me. I must admit that at moment I was not in the mood for an enema. I would rather have continued sleeping.
The warm soapy enema was not erotic as I had fantasied rather
It was uncomfortable and I whined through the whole enema. When I had taken the entire enema I made a dash for the bathroom. After expelling I returned to bed. I was pissed ! I let him know it and rolled over to sleep.
The motto " Be careful what you wish for !!! "