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

Other days

frozen yogurt

Frozen Yogurt Day
gum

Gum Day
bow tie

Bow Tie Day
ruby

Ruby Day
singles

Singles Day
tell a fairytale

Tell A Fairytale Day
lisp

Lisp Day
boba

Boba Day
coffee

Coffee Day
azonto is acceptable

Azonto Is Acceptable Day