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

Other days

prosecco

Prosecco Day
boba

Boba Day
law

Law Day
believe

Believe Day
kiss a brunette

Kiss A Brunette Day
tulip

Tulip Day
bow tie

Bow Tie Day
ask out your crush

Ask Out Your Crush Day
artists

Artists Day
buddy

Buddy Day