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

Other days

martini

Martini Day
book

Book Day
eat what you want

Eat What You Want Day
kiss a ginger

Kiss A Ginger Day
hoodie

Hoodie Day
pick me

Pick Me Day
offer

Offer Day
self care

Self Care Day
cat girl

Cat Girl Day
brow

Brow Day