A holiday for alcoholics. The one day of the year you can justify being an alcoholic.
Every holiday is a holiday for alcoholics.
Cinco de Mayo = National Margarita and Corona Day
Fourth of July = Bud Light Lime CranBrrrRitas for AMERICA Day
Thanksgiving = Three Gallons of Carlo Rossi and a Lot of Regrets Day
Christmas = Everything Left on the Liquor Shelf Ends Up in the Egg Nog Day
New Year's = Slamming Bottles of Cristalino and Pretending It's the Real Shit Day
Valentine's = Whatever is Available to Mask my Crippling Depression Over my Continued Inability to Get Laid Day
I mean, honestly, Memorial Day, Labor Day, Veteran's Day, Arbor Day, Columbus Day, Groundhog Day... There's no holiday that doesn't lend itself to drinking.
-EDIT- And Halloween! I can't believe I forgot Halloween, a holiday which ONLY EXISTS because otherwise reasonable adults decide they need to get fucked up on pumpkin schnapps and dress like a slutty werewolf in the hopes of drunkenly banging that dude in the Batman pajamas who turns out to be their daughter's pre-school teacher. If you want to complain about holidays for alcoholics, Halloween is the only argument you need. It's the ultimate trump card.