Bottle Cap Discs
Bottle caps have a thin layer of plastic inside. Back when not everything was digitized, these used to inform you if you’ve won any prizes- some companies still do this, but more often than not you’ll find codes instead nowadays.
While they’re helpful for this purpose, this isn’t actually why they’re there, as you’ve probably noticed bottle caps without prizes still have them. They’re there in order to prevent the drinks from going flat, adding another layer of protection. If you remove them and put the cap back on, after a while you’ll notice your drink tastes a little different.
