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

Other days

gum

Gum Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
embarrass your best friend

Embarrass Your Best Friend Day
polyamory

Polyamory Day
nae nae

Nae Nae Day
special education

Special Education Day
martini

Martini Day
hiv awareness

Hiv Awareness Day
bow tie

Bow Tie Day
raise awerness of zeus

Raise Awerness Of Zeus Day