FYI: Drinking all day counts as a reason.
You can have something like this for breakfast and no one will judge you, because you're just being patriotic.
Source: imgur.com
In fact, you can binge drink all day!
And if people question any of your binge drinking or potato-eating ways, you can just remind them of this terribly accurate Irish food pyramid.
Source: blogs.lynn.edu
Bountiful meat and potatoes? Today it's yours — eat up!
Source: aspoonfulofthyme.blogspot.com
It's a holiday where religion, ethnicity, hell, even appropriateness are thrown out the window: Non-Irish people can freely celebrate.
Looking at you, Ilish.
Source: imgur.com