I originally thought the lyrics of "Perfect Day" by Lou Reed were "You're going to reap, just watch yourself!" and it was meant as a sort of thread, like Watch Your Back!!
It was after a few years I realised that it's actually "You're going to reap just what you sow" which makes more sense but isn't as funny.
A childhood belief about misheard lyrics

others believed things like this
- I thought the lines in the sky left behind by airplanes were "sky scrapers". Makes sense.Anon
- I used to believe that when there was a tornado watch, you were supposed to sit down and watch the tornado.— Kay
- I thought a major general is more powerful than just a general (which still kind of makes sense to me)— Demond
- when i was little i thought that when we die we become stars and watch over our family that is still alive— josh
- When I was a little I thought TV was full of tiny books and we would watch one every day— Amine
- I thought that psychological torture involved forcing people to watch really sad movies!— Elviessa