Are you talking about the thing they insert into the urethra? Because that is a sex toy it’s definitely something they use in bdsm. I think it’s quite popular because in most stories involving BDSM they always end up using it. Hope this helps!
Its just like how the breast cups were originally for bring out breast milk but there's a sex toy variation
I used dilators (the urethra thing) with my ex boyfriend. He loved it. So yes it’s a thing bdsm-er are using (in rl).
The prostate is actually within the penis and can be stimulated directly through use of a sounding rot (urethra thing) as opposed to the indirect stimulation done anally, so I'd say that's the biggest appeal of it. There's also the masochistic appeal of it and that once the pain isn't as bad, the walls inside the penis can be erogenous as well
So I’m not gonna comment on the non-con part since I saw the tags and knew what I was getting into. I do wanna talk about the urethra that always seems to be used in either femdoms or bdsm bl does anyone actually like using it like this? I honestly thought it was a sex toy like nipple clippers or something until I googled that it was used for medical purposes