Oops, it doesn't look like 'Kiss My Ass day' is a national day..

Other days

cuddle up

Cuddle Up Day
boba

Boba Day
ruby

Ruby Day
one

One Day
ask out your crush

Ask Out Your Crush Day
aloxolt

Aloxolt Day
gum

Gum Day
youth

Youth Day
reading

Reading Day
kiss a brunette

Kiss A Brunette Day