That one time Batman became a mermaid, aka the Silver Age was weeeeeeeeeeeeeeird, dude.

Na Na Na Na Na Na, BatMerman!

So did they just hand out free cocaine at DC Comics back then or what? Normally, I would just leave this here without comment, but I'm sorry, I just have to have some context, because that shit is just bananas.

To Google!

Okay, so after way more Googling than what was probably needed, I finally tracked it down! It comes from Batman #53 from 1949, in a story called appropriately "Batman Under the Sea". Sooo, this was more Golden Age shenanigans than Silver Age WTF.

h/t DailyDCU for the picture.