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

Other days

buddy

Buddy Day
stress awareness

Stress Awareness Day
get funky

Get Funky Day
first love

First Love Day
lost sock memorial

Lost Sock Memorial Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
azonto is acceptable

Azonto Is Acceptable Day
bubble bath

Bubble Bath Day
cuddle up

Cuddle Up Day
special education

Special Education Day