I once was dating an older woman who was pretty much open anything I dreamed up -- erotic enemas, anal play, anal sex etc.
When I announced one evening that I was going to spank her bare bottom after her enemas, she got panicky.
I laid her naked on my long bathroom vanity with her lovely ass hanging over the edge of the basin and proceeded to shave her vulva bare before starting her three colon tube high enemas.
After the last enema, I put her back on the vanity and gently washed and dried her bottom.
I let her down and lead her into my living room and put her across my knee and a started a mild, slow hand spanking.
I alternated cheek to cheek with the intention of simply warming her shapely firm cheeks before fucking her silly.
I was lightly spanking, rubbing and massaging her ass and enjoying the view and sensations when she said, "Harder."
I upped the severity and speed of the strokes. She arched her back, let out a squeal and squirted all over my legs, rigid dick and sofa.
As her breaths came in gasps, I reached for her juices, lubed two fingers and easily slid them into her rectum where she immediately squirted again.
The rest of the time we dated, she never hesitated when I told her I was going to spank her.