Oops, it doesn't look like 'bra no bra day' is a national day..

Other days

boyfriend

Boyfriend Day
martini

Martini Day
kiss a brunette

Kiss A Brunette Day
artists

Artists Day
fiancee

Fiancee Day
girl friend

Girl Friend Day
slime

Slime Day
pick me

Pick Me Day
bow tie

Bow Tie Day
believe

Believe Day