Oops, it doesn't look like 'con air appreciation day' is a national day..

Other days

frozen yogurt

Frozen Yogurt Day
slime

Slime Day
kale

Kale Day
hoodie

Hoodie Day
boy friend

Boy Friend Day
tulip

Tulip Day
bubble bath

Bubble Bath Day
artists

Artists Day
girl friend

Girl Friend Day
gum

Gum Day