Oops, it doesn't look like 'flip flop snot day' is a national day..

Other days

artists

Artists Day
kale

Kale Day
ponytail

Ponytail Day
cuddle up

Cuddle Up Day
nae nae

Nae Nae Day
self care

Self Care Day
martini

Martini Day
aloxolt

Aloxolt Day
polyamory

Polyamory Day
slime

Slime Day