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

Other days

cursing

Cursing Day
chocolate milkshake

Chocolate Milkshake Day
healing

Healing Day
self care

Self Care Day
buddy

Buddy Day
ruby

Ruby Day
pumpkin

Pumpkin Day
unicorn

Unicorn Day
self appreciation

Self Appreciation Day
book

Book Day