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

Other days

self care

Self Care Day
kale

Kale Day
promposal

Promposal Day
latina equal pay

Latina Equal Pay Day
frozen yogurt

Frozen Yogurt Day
tulip

Tulip Day
artists

Artists Day
offer

Offer Day
stud

Stud Day
boyfriend

Boyfriend Day