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

Other days

tulip

Tulip Day
donate your hair

Donate Your Hair Day
bow tie

Bow Tie Day
self care

Self Care Day
carpenters

Carpenters Day
china

China Day
aloxolt

Aloxolt Day
artists

Artists Day
bubble bath

Bubble Bath Day
stud

Stud Day