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

Other days

boba

Boba Day
self appreciation

Self Appreciation Day
bow tie

Bow Tie Day
slime

Slime Day
buddy

Buddy Day
azonto is acceptable

Azonto Is Acceptable Day
unicorn

Unicorn Day
one

One Day
prosecco

Prosecco Day
bonang

Bonang Day