My iPhone 4 didn't have Siri, but I used it on another friend's phone and we literally spent all day trying to make her say certain things.
Now that I have the iPhone 5S, I do the same thing, and it's even better. She never glitches, she's not afraid to tell you "where to go and how to get there" using Google and your location. Kind of like an ex lover if you know what I mean.
The randomist thing that was done was when I was playing around, I said something along the lines of "where can I get tea", and she provided the link to Mr. T's page on Wikipedia. I guess she doesn't like tea..
Siri was greatly improved in iOS 7. The original version was pretty bad, including that it didn't recognize anything in Canada. I have an iPhone 4S and it works great for me. As you probably know, you can switch between a female or male voice as well.
I'm in Toronto and have a brother out in Vancouver. He's done some interesting things with Siri, including sending me text messages and emails that were dictated. They came through flawlessly.