Because hitting things with a bat is kind of the Joker's forte.

Once you remove all the rules and ceremony, baseball boils down to one thing -- hitting something as hard as you can with a solid wooden bat.

Ladies and gentlemen, the Joker is all about hitting things (players/mascots/hot dog vendors) with a solid wooden bat (or crowbar, or eel, or fish, or electrified tennis racket.)

Made from 100% cotton, our Joker Killing Joke Men's Baseball T-Shirt features that striking image from Alan Moore and Brian Bolland's seminal graphic novel, The Killing Joke.

And yes, that's the Joker's usual reaction after hitting something with a bat.

Did I mention this was a baseball t-shirt? 

This Joker Baseball t-shirt for men also features white 3/4" sleeves sporting illustrated (and hastily hand-painted) "HA-HAs."

Because after the Joker cripples Batgirl and tortures James Gordon, he laughs about it. A lot.