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

Other days

cuddle up

Cuddle Up Day
tulip

Tulip Day
brow

Brow Day
prosecco

Prosecco Day
promposal

Promposal Day
kiss a brunette

Kiss A Brunette Day
bow tie

Bow Tie Day
boy friend

Boy Friend Day
gallery

Gallery Day
fiancee

Fiancee Day