Oops, it doesn't look like 'checkerboard day' is a national day..

Other days

one

One Day
ormille

Ormille Day
pick me

Pick Me Day
bonang

Bonang Day
cuddle up

Cuddle Up Day
cat girl

Cat Girl Day
comfy

Comfy Day
lumpy rug

Lumpy Rug Day
my little pony

My Little Pony Day
promposal

Promposal Day