Actually I know a lab that ordered a large set of glassware from China directly from factory and erroneously received a different set of glassware. Turns out the same factory makes lab glassware and those kinky glass cocks and buttplugs to be filled with hot or cold water. What's even funnier, the senior PI genuinely had no idea wtf that is and went ahead asking colleagues - people around the globe - what they think this stuff would mean, what weird technology is that.

Before you ask - I don't know the name of the factory, but probably it's easy enough to find on aliexpress, I'm into different stuff. Buying directly from manufacturer is better than buying from local reseller IMO. The best thing for a chemist in this category is probably buying lubricant components in moderate bulk and mixing them yourself so as not to worry about shelf life and be as allergen free as possible.

If the OP question is genuine - this thing is supposed to occasionally rotate around held by the neck, so the bottom has minimal footprint thus it does not hit anything. And this is the most stable and easy to manufacture shape for that.