Oops, it doesn't look like 'championship and conference championship on the same day' is a national day..

Other days

promposal

Promposal Day
ask out your crush

Ask Out Your Crush Day
pumpkin

Pumpkin Day
aloxolt

Aloxolt Day
self care

Self Care Day
self appreciation

Self Appreciation Day
fiancee

Fiancee Day
ruby

Ruby Day
gum

Gum Day
bubble bath

Bubble Bath Day