OK. That makes sense now. I can see where Americans who have not been overseas would call them Grolsch bottles, but I prefer to say "flippes" or "Grolsch-style" as you meant to say.
I have over 100 Grolsch bottles and several hundred more German "flippies"...as we GI's called them in Germany.
I never heard of them called "snap caps", but that's not saying someone somewhere called them that.
I also have about 7 - 2 liter flippies that are decorative and used for display.