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

Other days

stress awareness

Stress Awareness Day
bounce

Bounce Day
one

One Day
first love

First Love Day
hoodie

Hoodie Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
offer

Offer Day
cursing

Cursing Day
my little pony

My Little Pony Day
chocolate milkshake

Chocolate Milkshake Day