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

Other days

promposal

Promposal Day
cuddle up

Cuddle Up Day
first love

First Love Day
self care

Self Care Day
nail polish

Nail Polish Day
pumpkin

Pumpkin Day
bounce

Bounce Day
unicorn

Unicorn Day
stud

Stud Day
offer

Offer Day