Batchick
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Batchick is a comic book series sold at The Android's Dungeon & Baseball Card Shop.
History
Batchick can be seen on a rack of comics when Bart and Milhouse are discussing the differences between Radioactive Man and Radiation Dude.
The cover contains a picture of a woman wearing a purple Batman-esque costume, with large bat wings on the back.
Behind the Laughter
The comic is a reference to the various female versions of Batman, most likely Batwoman.