Don't Drink Green Beer!
Smithwick's (pronounced "Smithick's" or "Smiddick's") is brewed in the 12th Century St. Francis Abbey in Kilkenny, Ireland (I've been there and tasted my first pint of Smithwick's in a nearby pub).
An Irish ale brewed in a Franciscan Abbey - how Catholic can you get?
And don't drink that black stuff called Guinness either! No self-respecting Catholic should drink something its founder called "Black Protestant Porter":
...It was in the 1790s that Guinness began producing what became its trademark product, a rich dark porter that came to be known as stout. Originally developed in London, it derived its unique color and flavor from barley that was roasted. Interestingly, Guinness called his brew "Black Protestant Porter," a name that reflected his opposition to the United Irishmen led by Wolfe Tone (in the nineteenth century the Guinness family mellowed a bit and became supporters of Catholic emancipation).
In recent years, Murphy's Irish Stout emerged as a rival to Guinness, first in Ireland and eventually in Europe and the U.S. Murphy's, of course, was no upstart operation. The original brewery opened in Cork in 1856. Like Guinness, it offered a hearty stout, but with a distinct flavor. The company also benefited from rising nationalist sentiment as a result of the Troubles. Simply put, Murphy's came to be identified with the Republic of Ireland while Guinness, especially for those who knew the company's history, seemed more and more identified with the 18th century Protestant Ascendancy...