My husband's Irish and Scottish. I'm Scottish, Italian, &... List goes on a bit. :)
I HATE GREEN BEER. Sure, it looks cool. But so did kool-aid when we were kids and we'd drink it for the color. We are ADULTS. They buy the cheapest beer they can and add coloring to it. And then charge you $4+ a pint for it. They see all of you "Everyone's Irish on St. Patrick's Day!" people and laugh allllll the way to the bank. Way to go.

Aside from the grossness, if you really were all about the Irish, you'd drink a Guinness or Smithwick's (pronounced Smit-icks, by the way) or Harp. Really, everyone should have a pint of Guinness on St. Patrick's Day. Having been to Dublin and toured the Guinness factory and been in shear awe of the awesomeness of Arthur Guinness, you owe it to 'em.
I'll leave you with a song about green beer (in case my demands weren't enough):
photo from: http://www.beerhelps.com/types-of-beer-an-overview/stout-beer-overview