2 Karat Engagement Ring

Two karat engagement ring. Um, that is, two carrot ring ... 'nuf said! Source.
Industrial Wedding Rings

Not sure which ring is supposed to belong the bride, and which to the groom. Wait a second ... let's see ... oh, right, got it! Giggle. Source.
Chest of Drawers Ring

Great! A ring where you can keep small and important objects. What are those round pieces of jewelry called again? Source.
Cup Ring

It's hot. You're thirsty. You come across a cool stream. You drink from it, but then you need to get on your way. No Nalgene bottle! What to do? Wait a minute, I have a liquid-holding vessel right here on my finger. Thank god!!! Source.
Vacuum Tube Ring

That AM radio set not working? No problem, I have the hardware here right on my finger. But, oh, wait, that would leave me with ... um, an incredibly industrial, ugly piece of metal. Sorry. Get XM (or is that Sirius?). Source.