"Foo" is my favorite word. I use it all over the place. When programming, it is the name of my quick junk files... it is a temporary variable name while i figure out code. We programmers love our foo.
For those that want the origins and etymology, there is a great RFC about it:
Copyright © 2006-2008 Corey Goldberg
Disclaimer The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.