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

Other days

boba

Boba Day
tell ur crush you like them

Tell Ur Crush You Like Them Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
emoji

Emoji Day
latina equal pay

Latina Equal Pay Day
blanket fort

Blanket Fort Day
cursing

Cursing Day
special education

Special Education Day
hiv awareness

Hiv Awareness Day
fiancee

Fiancee Day