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

Other days

coffee

Coffee Day
ask out your crush

Ask Out Your Crush Day
aloxolt

Aloxolt Day
comfy

Comfy Day
brow

Brow Day
hoodie

Hoodie Day
donate your hair

Donate Your Hair Day
my little pony

My Little Pony Day
slime

Slime Day
nae nae

Nae Nae Day