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

Other days

hot chocolate

Hot Chocolate Day
buddy

Buddy Day
artists

Artists Day
cursing

Cursing Day
chocolate milkshake

Chocolate Milkshake Day
martini

Martini Day
bow tie

Bow Tie Day
aloxolt

Aloxolt Day
promposal

Promposal Day
self care

Self Care Day