Oops, it doesn't look like 'no shoes day' is a national day..

Other days

law

Law Day
bow tie

Bow Tie Day
slime

Slime Day
lash

Lash Day
tulip

Tulip Day
offer

Offer Day
my little pony

My Little Pony Day
chocolate milkshake

Chocolate Milkshake Day
artists

Artists Day
singles

Singles Day