Ass Pull: Played for Laughs. Poochie is sloppily killed off in one cartoon, with a crude movement of cels and stuck on note saying he died on the way to his home planet. Everyone hated Poochie so much they didn't care, they erupted in applause.
Designated Monkey: In a parody of standard cat and mouse cartoons, Scratchy is brutalized just because he's the cat.
Dude, Not Funny!: Often from Marge, though there are episodes that touch a nerve with even Bart, Lisa, and Homer, albeit usually connected with some dilemma they are undergoing at the time. An example is the episode "Lisa the Vegetarian" where Lisa doesn't laugh along with Bart (as she usually does) because "violence against animals is not funny".
Hilarious in Hindsight: In "The Tears of a Clone", Scratchy has died, and Itchy realizes that Victory Is Boring and life is meaningless without his Arch-Enemy around, so he creates a cloning machine and creates more clones of Scratchy so he can kill them. However, he grows tired because of the way the machine spits out clones, so Itchy creates a killing machine and makes an endless slaughterfest. Over fifteen years later, we get the Treehouse of Horror XXVI segment "Wanted: Dead, then Alive", whose plots became strikingly similar to "The Tears of a Clone", with Sideshow Bob as Itchy and Bart Simpson as Scratchy; the Reanimator in place of the cloning and killing machines; and a slightly different ending, which goes well with Bart and his family finally triumphing over Bob after all the ordeals the boy has gone through.
Worse yet is that the children viewing the show always laugh at the horrific carnage being displayed. It's portrayed in a comedic light as a satire of violence in American media, but it's still a little disturbing.