Oops, it doesn't look like 'what if cats and dogs had opposable thumbs day' is a national day..

Other days

Girl Friend Day

Carpenters Day

Donate Your Hair Day

Nae Nae Day

Ask Out Your Crush Day

Tell Ur Crush You Like Them Day

Lumpy Rug Day

Cuddle Up Day

Lost Sock Memorial Day

Frozen Yogurt Day