I also had a fun encounter in the grocery store. I was wearing a T-shirt (and I forget which one now) that had something about Supernatural on it. The cashier saw it and said "Oh, I love that show!" We didn't talk much though, because there was a line. Enough to know that Sam was her favorite though!

One other time I was wearing another shirt that said Winchesters when I went to pick up a pizza. A guy in line asked if it was the town Winchester (which is two towns away)and a teenager standing nearby said "no, it's a TV show." Again, long line, so that was the extent of the conversation. :)