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

Other days

bow tie

Bow Tie Day
tulip

Tulip Day
brow

Brow Day
nail polish

Nail Polish Day
eat what you want

Eat What You Want Day
cat girl

Cat Girl Day
prosecco

Prosecco Day
self care

Self Care Day
stud

Stud Day
coffee

Coffee Day