Code Golf is a time honored tradition of taking simple software problems and torturing their solutions into code tightened to the point of obfuscation... the fewer characters, the better your score.
Ruby metaprogramming gives us some interesting tools for playing the game, and Ruby 1.9 has an interpreter that gives us a leg up, allowing us to shorten method calls to the shortest name that uniquely identifies them. This blog post goes into the technique.
Why is this useful? Learning these techniques teach you the corners of the language that can turn you into a Ruby Maestro.