So one time (like two months ago) my dad and sister were completely shocked to discover that "Twinkle, Twinkle Little Star" and "The ABC Song" were actually the same tune. Until that moment, they had gone their whole lives not knowing this.
I made fun of them.
Imagine my embarrassment when I wandered into Albertson's for some lunch yesterday and it dawned on me that "deli" is short for "delicatessen."
Don't worry, Pop and Sis, I made fun of myself.
What about you? Any sort of silly things you probably should have known a long time ago but for whatever reason just figured them out?