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

Other days

Lumpy Rug Day

Tulip Day

Stud Day

Promposal Day

Raise Awerness Of Zeus Day

Embarrass Your Best Friend Day

Kale Day

Get Funky Day

African Immigrant And Refugee Hiv And Hep Awareness Day

Martini Day