St. Patrick's Day, of course, is the annual green-wearin', beer drinkin', boisterous celebration of all things Irish.

But if you want to really celebrate the Emerald Isle on St. Paddy's Day, put down that mug of green beer and turn to the dark side, says Guinness brewmaster Fergal Murray.

That green fizzy stuff in your glass is no more Irish than Budweiser. But, Murray says, a pint of Guinness Draught is always straight from the brewery in Dublin -- no matter where on Earth you're quaffing it.

"All of the Guinness Draught is brewed at St. John's Gate (the name of Guinness's brewery) here in Dublin," says Murray, who is one of numerous brewmasters tending to the crafting of Guinness at 49 breweries around the world.

The Dublin-brewed Guinness Draught, which is available in kegs, cans and bottles here in the United States, remains constant, but there also are a number of other styles of Guinness brewed at these worldwide facilities -- some of which most Americans have never laid lips on. Each of these "local" Guinness styles is a bit different, and each caters to diverse local tastes. For instance, the Extra Stout, which is brewed in Canada and distributed in several countries, is a version of Guinness that is much stronger in flavor. The Foreign Extra Stout, sold in Africa, the Caribbean, and in Asian countries, is described by Murray as "big and bold." In Nigeria, Guinness is made from sorghum instead of malted barley because, until recently, it was illegal to import barley to Nigeria.

"We continue to brew Guinness with sorghum in Nigeria, because that's the flavor people are used to," Murray says. (Beer lovers with gluten intolerances should take note: Murray says the Nigerian Guinness could possibly be gluten free.)

But even all of those beers get a slight infusion of beer from the mother ship, Murray says, which has been brewing Guinness since 1759.

"We blend some of the beer brewed at St. John's Gate with all of those other beers brewed at all the other breweries across the world," he says. "That way, there's a little bit of Ireland in each beer.

"But Guinness is truly a global brand. It transcends all borders and cultures. It's not just Irish. It is the national product of each place where it is brewed."

Maybe so, but the product is all "Erin Go Braugh" on St. Patrick's Day. On that one day alone, an estimated 13 million pints of Guinness are raised across the planet -- more than 150 pints every second, according to a brewery news release. Here in the United States, revelers quaff 3.5 million pints on St. Patrick's Day alone.

If Guinness isn't your cup of, well, beer, Murray only asks that you make your beer choice on St. Patrick's Day an authentic Irish one. (Harp and Smithwick's also are brewed by Guinness. Other readily available beers from Ireland include Beamish and Murphy's Irish Stout.)

So, go ahead, get your green on March 17 -- just keep it out of your pint glass.