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

Other days

me

Me Day
bow tie

Bow Tie Day
blanket fort

Blanket Fort Day
tell a fairytale

Tell A Fairytale Day
pampering

Pampering Day
tell ur crush you like them

Tell Ur Crush You Like Them Day
prosecco

Prosecco Day
emoji

Emoji Day
ask out your crush

Ask Out Your Crush Day
offer

Offer Day