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

Other days

donate your hair

Donate Your Hair Day
youth

Youth Day
gum

Gum Day
special education

Special Education Day
bounce

Bounce Day
blanket fort

Blanket Fort Day
martini

Martini Day
healing

Healing Day
bow tie

Bow Tie Day
lash

Lash Day