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

Other days

stud

Stud Day
comfy

Comfy Day
coffee

Coffee Day
mean girls

Mean Girls Day
stress awareness

Stress Awareness Day
lisp

Lisp Day
hot chocolate

Hot Chocolate Day
gum

Gum Day
nae nae

Nae Nae Day
ruby

Ruby Day