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

Other days

gum

Gum Day
prosecco

Prosecco Day
kiss a ginger

Kiss A Ginger Day
mean girls

Mean Girls Day
artists

Artists Day
tulip

Tulip Day
offer

Offer Day
kiss a brunette

Kiss A Brunette Day
hannah

Hannah Day
martini

Martini Day