Oops, it doesn't look like 'something left handed day' is a national day..

Other days

Hoodie Day

Kiss A Brunette Day

Get Funky Day

My Little Pony Day

Lisp Day

Embarrass Your Best Friend Day

Slime Day

Ask Out Your Crush Day

Tell Ur Crush You Like Them Day

African Immigrant And Refugee Hiv And Hep Awareness Day