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

Other days

gallery

Gallery Day
slime

Slime Day
promposal

Promposal Day
youth

Youth Day
pick me

Pick Me Day
pumpkin

Pumpkin Day
offer

Offer Day
eat what you want

Eat What You Want Day
bow tie

Bow Tie Day
comfy

Comfy Day