I was buying this travel guide to somewhere I was planning to visit (or no other reason than the place interested me) and this girl behind the counter made a comment about how she's always thought about going there after she graduated, but couldn't. To this I asked if she'd saved enough money for college (I swear blind she looked 16/17/18 tops). Don't ask me where it came from, but this girl looked young and it just came out before my brain had twigged my mouth was working.
Anyhow she gave me this startled look and said that was about to graduate from the same college I was at (she was an undergrad), and that she was moving with her husband to Chicago so he could study for a PhD there.
I don't think I've been so embarrassed since the time I told a woman with gray hair that she could apply for a bus pass at the same time as her Mum if she wanted to.
Come to think of it I really suck at judging people's ages. Note to self... always low-ball ages in future.
Anyway when she said that I felt old, I mean she didn't look mid-20s.