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

Other days

chocolate milkshake

Chocolate Milkshake Day
boba

Boba Day
bow tie

Bow Tie Day
fiancee

Fiancee Day
ruby

Ruby Day
aloxolt

Aloxolt Day
cuddle up

Cuddle Up Day
slime

Slime Day
nae nae

Nae Nae Day
coffee

Coffee Day