A federal appeals court affirmed Thursday that a 2008 South Park parody of a real-world video — “What What (In the Butt)” — did not infringe on the YouTube video of the same name. The decision upheld a lower court which sided with Viacom subsidiary Comedy Partners’ fair-use defense. More important, the outcome affirms the right that you can get an infringement case thrown out of court — via a fair-use defense — without having to go through an expensive trial.