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

Other days

african immigrant and refugee hiv and hep awareness

African Immigrant And Refugee Hiv And Hep Awareness Day
self care

Self Care Day
lisp

Lisp Day
china

China Day
prosecco

Prosecco Day
martini

Martini Day
lumpy rug

Lumpy Rug Day
bounce

Bounce Day
my little pony

My Little Pony Day
azonto is acceptable

Azonto Is Acceptable Day