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

Other days

boba

Boba Day
african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
martini

Martini Day
china

China Day
ask out your crush

Ask Out Your Crush Day
first love

First Love Day
pumpkin

Pumpkin Day
brow

Brow Day
pampering

Pampering Day
eat what you want

Eat What You Want Day