Design patents are totally different than regular patents though. I have never heard of anyone getting sued because of a design patent.

One instance I know of is when Gibson Guitars sued Paul Reed Smith Guitars over the single-cut design Gibson uses for its Les Paul guitars (and won).

No, you get sued then because of trade dress.

Try putting your own beverage in bottles shaped like Coke's iconic curve bottle. Then you'll hear of it.

That's trademark law. Not the same thing as patent law, which in turn is not the same thing as copyright law.

The design of a functional thing may be covered under a design patent; and indeed the Coke bottle shape is covered by such a patent.

Trademark law refers primarily to the design of nonfunctional things such as logos, the Deep Note sound, etc.