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

Other days

blanket fort

Blanket Fort Day
lash

Lash Day
artists

Artists Day
boy friend

Boy Friend Day
slime

Slime Day
hoodie

Hoodie Day
kale

Kale Day
youth

Youth Day
ask out your crush

Ask Out Your Crush Day
stress awareness

Stress Awareness Day