Oops, it doesn't look like 'slap your coworker day' is a national day..

Other days

Prescription Drug Take Back Day

One Day

Carpenters Day

Pampering Day

Get Funky Day

Embarrass Your Best Friend Day

Azonto Is Acceptable Day

African Immigrant And Refugee Hiv And Hep Awareness Day

Aloxolt Day

Cuddle Up Day