You can't tell me this isn't true!

Martian Manhunter cosplayed as Sailor Mars aka Hino Rei from the manga/tv series Pretty Guardian Sailor Moon. Batman was a fan of Sailor Moon apparently because he remembered that Hino Rei was Sailor Mars.

Mars, heh, get it?

....WHY DIDN'T I MAKE THE CONNECTION SOONER?! I HAVE BROUGHT SHAME UPON MY FANBASE!!!!

it's such a clever pun. So clever, it hid behind TWO fanbases.

There's a few different translations, but the most commonly agreed upon is "Fire Soul".