For me, the first big one was songs that were popular when I was in high school getting air play on classic rock stations.
The other, needs a little context....
My entire life, people have always thought I was much younger than I am at any given time. My whole childhood, adolescence, and adulthood. When I was the oldest one on my tee-ball team at the age of 7, the coach talked to my mom about maybe I'm too young to be playing yet. When I was 10, people thought I was 7. When I was 13, people thought I was 10.... Skip ahead some years, I go back to school in 2011 at the age of 28. I befriend this dude in my chemistry class. He asks me when I graduated. I said 2007. He was like 2007????? Then I was like oh you mean, high school or college? He goes high school! Then I go oh, 2002 then. I graduated from college in 2007. He was shocked. He thought I was straight out of high school like he was.
Now keep in mind, I've never bought alcohol before, because I was never a drinker. Any time I ever drank, someone else bought it (pretty much always my parents).
Also, keep in mind, that back when I was a KID, I don't know what the law is now, but in California the law was/is if you are buying alcohol, the cashier legally HAS to card you if you even LOOK like you COULD be younger than 35.
So a couple or so years ago, when I was around 36, me and my singer are on our way to band practice, and we get our normal pizzas and we stop at a convenience store, because he wants some beer. He asks me to buy it for him since he was low on money at the time and he will get me back (he is definitely good for it, I have lent him a ton of money and he always pays me back very quick and I never even have to remind him). So I bring the beer to the counter and I was I like "oh I guess I have to show you my ID." The cashier was like, "That's ok, I can see the grey in your hair." I was absolutely stupefied.