If you can't hear this, you're old.

Some nerds in England have developed a cell phone ring tone that adults generally can't hear, but kids can. Apparently its becoming popular in schools so that kids can keep their cell phones on in class.

You can listen to it here - I'm 28, and I can hear it fine. But I spent 9 years studying music, so maybe I'm an aberration. Or maybe I'm just young.