Once you are out of your 20's, moments begin to happen that make you think, "I am not as hip as I used to be." (Well actually, when you start using the word 'hip', you're pretty much done.) Moments where you recognize that the world has moved on while you weren't looking. Moments like when you look at the Billboard top 10 and think, "I wouldn't buy any of this", which is quickly replaced with, "I don't recognize any of these artists."
I had a moment somewhat like that this weekend. Fortunately, it wasn't one of those brutal moments that slaps you upside your head and says, "you're old!" though.
We were hanging out with some people in their 20's, and they were quoting a YouTube video. I actually knew the video, so I didn't feel all that out of it. But I recognized that where we used to quote Seinfeld episodes and the like, people now quote stuff from the internet. Videos and other memes are what pass for common culture now.
Not that quoting crap on the internet is any worse than quoting crap on tv, it is just different. And a sign that the world is moving on, with or without me.