It's good to know that, as a non beer-lover, I can feel righteous in not celebrating this day by drinking Guiness.
It's a funny thing, the way symbols are derived at all - and how they evolve.
Pink, that emblematic color of nipples now so ubiquitously associated with corporate breast cancer marketing campaigns, vapid "femininity", and razors I am allowed to use as a woman, was actually once most popular for MALE children.
The frog, sometimes considered emblematic of the French (are kids still aware of that old one anymore, though?), who sometimes are caricatured as profligate and promiscuous lovers, is deeply associated with the idea of fidelity.
Indeed, the dog - widely loved most for its faithfulness and loyalty - is repurposed linguistically to refer to profligate and promiscuous lovers, generally male ones.
So it is an interesting history - Guiness, so PR-ready in its shorthand Irishness - is actually a centuries-deep English product, and generations of its proprietors were anti-union and anti-everything (Americans?) expect in a broad-strokes portrait of "What Is Irish" ... For eighty-four years, indeed, the company has been based in London, apparently.
Side note: intoxivation, spotted in a link at the bottom of this article, is a delicious coinage.