Even if you’re the kind of person who scorns tasteless green beer, you might enjoy a Guinness for Saint Patrick’s Day. And why not? Unlike shamrock pins and wild partying sure to take place on March 17th, Guinness drinking really is a longstanding tradition in Ireland, as well as the Irish diaspora. But it’s a folk tradition that’s inextricably tied up with almost a century of commercial advertising, according to Brenda Murphy, a gender studies professor at the University of Malta.

Murphy visited pubs in Dublin and Waterford, Ireland and in London and New York, speaking with Irish citizens and first-generation Irish immigrants. She also showed them Guinness ads from 1928 on and asked their opinions on them. Murphy found that pub patrons were more than happy to talk about Guinness at great length. Many waxed eloquent about the effort to find the “perfect pint.” That meant trying out different pubs, looking to see how the product was stored, and checking how many people in a given bar were drinking Guinness and whether the pints in front of them had the right amount of head.

Another frequently repeated statement was that it’s nearly impossible to enjoy the first Guinness you ever drink. Acquiring a taste for the stout meant being part of a community (usually an all-male one) that insisted on the brand as a symbol of belonging. One Irish man described having his first Guinness with family members who insisted that he wasn’t allowed to drink “jungle juice”—any foreign beer—in their company.

Guinness drinkers also associated the brand with all kinds of positive values. They cited the company as a great employer that offered a solid career and a good pension and bragged that it was the biggest brewery in Ireland “as if someone in the family was responsible for this fact,” Murphy writes. Many also recalled the company’s old advertising slogan “Guinness is good for you” and cited its use as a tonic for sick children and nursing mothers.

More modern advertisements had also become part of Irish identity. One man described returning to Ireland after traveling abroad and seeing references to a 1994 TV advertisement everywhere. The commercial, titled “Anticipation,”  shows an actor dancing to the song “Guaglione” while a barman slowly fills a giant pint. The ad formed the basis for screen savers, internet jokes, and actual dancing at nightclubs and barbecues.

While the drinkers in Ireland and abroad shared many of the same associations and memories around the Guinness brand, Murphy did find one distinct difference. When asked to free-associate words connected the stout, those in Ireland rarely referenced its connection with the Irish nation. But Irish immigrants in London and New York often came up with words like “Ireland,” “Dublin,” and “shamrock.” Which explains why so many of us in the U.S. choose to drink this challenging beer on the day we celebrate Irish identity.