Okay, so, here´s the full story from the beginning. There was once a law, created by a being of darkness called ´The Derailer´ that restricted cartoon characters from different shows interacting with each other. Any character caught interacting with someone outside of their own show would get it canceled before it finished. It also meant that nobody could go out-of-character or break the fourth wall.
For the cartoons on Cartoon Network, one of the 8 networks (one of which wasn´t a network, but still made cartoons) which this applied to, they had an intense struggle with following this rule (Seriously, watch Chowder, Ed, Edd n´ Eddy, or Gumball and you´ll get it), and began to riot. Unfortunately, The Derailer had corrupted some of the biggest faces in cartoon history, and since they made the rules, it seemed as if the ´no sociality or reality´ ban would ever be lifted.
When the toons of Adult Swim decided to side with them (they had to be first because of AT&T), the Derailer began to lose control of the famous cartoon faces, and as the characters of the shows from Nickelodeon, FOX, and Comedy Central joined, it seemed as if he still wasn´t gone for good. Sooner or later, the Netflix, Discovery Family, and Disney XD shows were on their side as well, and the Derailer was erased from the Tooniverse for good.
Now the law was no longer in action, all 8 cartoon channels (I know Netflix isn´t a channel, but they still make cartoons) were united. It took them a while to grow friendly towards each other, but their friendships became firm, and some adult cartoons even vowed not to swear or expose their... private parts... or show violence around the kids´ cartoons.