Michael Kaplan called my attention the latest Unicode fashion accessory:

For those who don't get it, that funny little question-mark character is what Mac users see when their computers don't have the right font to display a given character (or if the Web browser gets a bit confused about what font to display). Just because Unicode allows you to display the world's major languages on a Web page does not guarantee that your Web users have the right fonts on their end.

Windows users see blank boxes -- and yes there's a shirt for Windows users as well:

The shirts are available from Cafe Press. I wonder if I can get one in black...