Thing I Definitely Should Have Known Earlier In Life
I recently found out that a pickle and a cucumber are the same thing. I had no idea. Yeah, laugh it up. Real fucking funny. Thankfully, I didn't have a strong opinion that pickles were definitely not cucumbers, so it wasn't hard for me to change my mind on this whole cucumber-pickle thing.
There's probably a life lesson here ("Look at how quickly you learn when you don't have strong opinions!"), but it's more likely that I should have just known what a pickle was.