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

Other days

youth

Youth Day
gum

Gum Day
latina equal pay

Latina Equal Pay Day
nae nae

Nae Nae Day
ormille

Ormille Day
book

Book Day
ruby

Ruby Day
offer

Offer Day
hoodie

Hoodie Day
hot chocolate

Hot Chocolate Day