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

Other days

cursing

Cursing Day
self care

Self Care Day
ponytail

Ponytail Day
bow tie

Bow Tie Day
book

Book Day
boba

Boba Day
martini

Martini Day
polyamory

Polyamory Day
carpenters

Carpenters Day
self appreciation

Self Appreciation Day