I personally would prefer Platypus Day. There’s an animal that deserves to be celebrated. It’s a furry, poisonous rat-duck. A platypus is practically a living Pokémon.
But somehow the groundhogs won out. I suspect bribery.
For the record, today I will honor platypi in my heart. Although Wikipedia tells me that platypi is incorrect and I should say platypuses or platypodes. Also, they are venomous and not poisonous (venom is injected, poison is consumed).
To which I say: poisonous rat-duck sounds better than venomous rat-duck, and platypi has a satisfying faux-intellectual ring to it. Let rhetoric prevail, and let the poisonous rat-ducks have their day on the calendar!