Alright Apple, how in the hell are you going to get out of this one? You were awarded a trademark for "There's an app for that" (
http://mashable.com/2010/10/11/apple-trademark/ ). But, this is Sesame Street. However, Sesame Street will be selling this episode one day, in which case they will be making money off of a product with your trademark without compensating you. But if you force them to pull this skit, they would have to remove the whole episode (because otherwise it would be too short to show later), unless they replaced it with something or overdubbed with something else, which I'm sure they'd rather not do. But if you touch this at all, the public and media will be all over it. However, if you don't, then any other company can use Sesame Street as an example of fair use, if you claim it to be so, so... I believe that one of your lawyers is now having an aneurysm.
Lesson learned: Trademark your witty memorable lines from marketing material prior to or as soon as possible after release; if you don't, then don't trademark them at all, or you might risk the "Sesame Street Catch-22".