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

Other days

cursing

Cursing Day
prosecco

Prosecco Day
ruby

Ruby Day
pick me

Pick Me Day
buddy

Buddy Day
my little pony

My Little Pony Day
fiancee

Fiancee Day
mean girls

Mean Girls Day
slime

Slime Day
eat what you want

Eat What You Want Day