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

Other days

fiancee

Fiancee Day
pumpkin

Pumpkin Day
tulip

Tulip Day
eat what you want

Eat What You Want Day
nae nae

Nae Nae Day
youth

Youth Day
lash

Lash Day
buddy

Buddy Day
boba

Boba Day
blanket fort

Blanket Fort Day