This happened today. Me and some friends were on a pub crawl. On the third pub we visited were in the beer garden. There were a lot of young school teachers in there. Apparently it's breakup day today. Anyway, at one of the other tables there was a sign that read "Reserved - teacher's only".
I thought that was amusing. Anyway, a group of teachers came and sat at the table, but the apostrophe went unnoticed. I thought it would be fun to point it out, so I said to one of them "As teachers, do you get a prize for pointing out the errant apostrophe?", at which point they noticed it.
They seemed quite impressed with this, and said that since I was the one who pointed it out, I win the prize. Then they gave me a piece of their cake. 🍰 👍
Very nice it was, too. Chocolate with little smartie type things on top.
Going forward, I shall be pointing out more apostrophes. 😄