In the vein of my previous TIL (Today I Learned) post, here's some more fun for you.
TIL. As in Today I Learned. As an internet meme, it refers to you recently learning something for the first time that is common knowledge to almost anyone else. Another way the game is played is to say "I was xx years old when I found out..." and the xx refers to your age now. Meaning that you were completely oblivious to it for your entire life.