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

Other days

lumpy rug

Lumpy Rug Day
reading

Reading Day
tulip

Tulip Day
lisp

Lisp Day
self care

Self Care Day
donate your hair

Donate Your Hair Day
blanket fort

Blanket Fort Day
first love

First Love Day
law

Law Day
bow tie

Bow Tie Day