For all you dirty-minded people who have opened this thinking its about human nipples in some kind of fetish... Shame on you!
This is about poultry nipple drinkers!
I bought a load of nipples online, just the nipples themselves, ready to screw into whatever.
I screwed one into a bottle lid, and hung the bottle upsidedown.
The chickens figured it out quickly, but the nipples don't seem to let any air back in. So the bottle sucks in slightly, then the vacume stops any more water coming out.
I pierced the bottle, which solved the vacume issue, but the nipples let out quite a lot in one go.
Are nipples supposed to be fitted to airtight containers?
Do I try a stiffer bottle?