Oops, it doesn't look like 'flag picks up with day' is a national day..

Other days

ponytail

Ponytail Day
pick me

Pick Me Day
ask out your crush

Ask Out Your Crush Day
chocolate milkshake

Chocolate Milkshake Day
reading

Reading Day
bubble bath

Bubble Bath Day
self appreciation

Self Appreciation Day
me

Me Day
emoji

Emoji Day
my little pony

My Little Pony Day