Er... I've had that done to me. It was a very thin stiletto that was the same width from tip to top rather than a regular heel that widens as it goes up to the shoe. My thought when she was doing it was of how she must be ruining her heel with the lube rather than some extreme excitement over it.

What was much worse than that was last Saturday when my Chicago Domme turned my cock into a bud vase by shoving the stem of an orange flower in it (this kind of "bright idea" is why I am not the largest fan of doubles). Not sure what that did since she did something much more painful with a sort of bumpy sound that she inserted and then squeezed my cock hard around it (that wss also was an electrical device that was hooked up to a control box). In the end, there was blood (enough so that I threw my underwear out the next morning) and a day of very painful pissing, but no hospital visit.

I like you erring on the side of safety, but there are definitely Dommes who love the act of "sounding" for the humiliation of shoving other things into cocks as well as urethral stretching using proper metal ones.