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

Other days

promposal

Promposal Day
get funky

Get Funky Day
believe

Believe Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
bubble bath

Bubble Bath Day
hiv awareness

Hiv Awareness Day
one

One Day
gum

Gum Day
bounce

Bounce Day
ask out your crush

Ask Out Your Crush Day