So, a $4 medical device with an unsanitary reputation and a number of sharp points? You bet your butt it's used for bonin'!
Gleefully sold as a sex toy, the Wartenberg (or "Wartenburg," as it is often called, presumably to prevent the ghost of the doctor who invented the instrument from rage-haunting the users' crotches) Pinwheel is commonly bought with items like these:
The pictures say "sex stuff," the titles say "We're not quite sure how you humans name things."
And there's nothing wrong with that; a little BDSM never hurt anyone (shut up, you know what I mean). However, a slightly more worrying aspect of the product is the fact that a) this is pretty much the cheapest thing Amazon offers in the sex toy category, and b) the product description features no hints on how to use it whatsoever. Combine these things, and you have a potentially hurtful-as-fuck medical tool in the hands of the kind of person who happily purchases $4 sex toys.
What I'm saying is that more than one doctor has probably spent some interesting hours trying to dislodge this thing from someone's urethra.