Me, after finding a cool stick with some heft to it:

“Any beasts want to tango with the apex predator and his tools of warfare?”

Whoville celebrating a holiday of cheer in winter, where they decorate everything in colourful lights and give presents means they have a winter season.

Celebrating “Christmas” as they call it, or “Christ’s mass” unabbreviated, probably means both “Christ” and “mass” means something to them. Of course one would reasonably assume Christianity exists then.

They could be celebrating the massiveness of someone who coincidentally has the same name, sure, but if no Christ exists in this universe, the person who translated it from Who-ish to English and called the festival “Christmas” instead of “Whonukkah” messed up badly.

Either that or the Portuguese discovered/conquered/colonized them in the 16th century and the population was catholicized by Jesuit missionaries. While they clearly redefined their own culture to be something unique after indepence, their former faiths have been forgotten, even by them.

Whothulhu will rise just the same.