So what you're telling me is that http://www.youtube.com/watch?v=PYmXFRnFat4&feature=related is just as random as http://www.youtube.com/watch?v=jaPAYnINMKQ I think not.
But then I grew up on shows like Rugrats and Angry Beavers, so naturally I'm spoiled to the cartoons of 2011.
Neither are random. Taking a clip out of context doesn't make it random. Marceline was intentionally freaking Finn out that episode and it finally culminated with Jake trying to kill Marceline, because Jake keeps catching the acts from the wrong perspective, so he thinks that Marceline actually did hurt those people. If you think that its random because Marceline ate the red off of his bowtie, its already been established since the very first Marceline episode that she doesn't drink blood, instead drinking the color red to sate her vampiric appetite.
In fact, its about as non-random as it gets.
Surely any cartoon will have randomness to it, but to claim that all of Adventure Time is random is total crap. Watch Susan Strong or Mortal Coil (especially Mortal Coil) and you'll see just how linear the show can be.