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

Other days

hoodie

Hoodie Day
bow tie

Bow Tie Day
slime

Slime Day
nae nae

Nae Nae Day
singles

Singles Day
bonang

Bonang Day
azonto is acceptable

Azonto Is Acceptable Day
unicorn

Unicorn Day
frozen yogurt

Frozen Yogurt Day
get funky

Get Funky Day