Saturday is Free Comic Book Day, when you can stock up on free comics, while Tuesday was National Superhero Day, when you could've ... loaded up on free doughnuts. But today? It's Batman Day. Apparently.

Sure, DC Comics long ago established Feb. 19 as Bruce Wayne's birthday, and then just last year declared July 23 as "Batman Day" as part of the promotional celebration of the Caped Crusader's 75th anniversary. However, this Batman Day is set aside to honor the anniversary of the character's debut in Detective Comics #27, covered-dated May 1939.

At least that's what the Days of the Year website tells us. There's no source listed for the observance, but we can only hope Batman Day was established by some long-forgotten congressional resolution or presidential proclamation (don't bet on it, though).

The problem (a problem?) with Batman Day is, of course, that while Detective Comics #27 sports a cover date of May 1939, the issue didn't arrive on newsstands on May 1 ... or any time in May, for that matter. It went on sale anywhere from a couple of weeks to a month earlier -- possibly April 18, or more likely March 30.

But, hey, much like Santa Claus, the spirit of the Dark Knights exists in our hearts year-round. We should treat every day like Batman Day! Look, Metro is already celebrating with a look at the Caped Crusader's 10 best comic-book moments.