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

Other days

frozen yogurt

Frozen Yogurt Day
slime

Slime Day
comfy

Comfy Day
fiancee

Fiancee Day
hoodie

Hoodie Day
self appreciation

Self Appreciation Day
bow tie

Bow Tie Day
tell a fairytale

Tell A Fairytale Day
blanket fort

Blanket Fort Day
aloxolt

Aloxolt Day