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

Other days

self care

Self Care Day
cursing

Cursing Day
boy friend

Boy Friend Day
buddy

Buddy Day
hannah

Hannah Day
lost sock memorial

Lost Sock Memorial Day
slime

Slime Day
tulip

Tulip Day
pumpkin

Pumpkin Day
bow tie

Bow Tie Day