Sonic

The headquarters for Sonic Industries, Inc. (Sonic Drive-In) are located in downtown Oklahoma City.

I'd like to talk to their marketing team sometime about happy hour. They say that happy hour (half-priced drinks) is from 2pm to 4pm. Since that's two hours, I think it should be called happy HOURS, not happy HOUR. It should not matter to me, actually, since the only thing I drink from Sonic is water, but it does.

What say you? Hour or hours?