There are Ad Hominem insults. There are Lame Comebacks. And then there are these — insults so trite and meaningless that one may as well have called the other person a "Big Stupid Doodoo Head". Young children will resort to using these because they either don't know any better, or have run out of things to say. When an adult uses these, however, it's a good sign that they don't have any real substance to back up their argument.
Sometimes Played for Laughs when it induces Felony Misdemeanor. Often involves Buffy Speak.
See also No, You, really the only appropriate comeback to such an insult.
Yu-Gi-Oh! The Abridged Series: the Pharaoh's best retort to Yugi's insults is something along the lines of "Yeah, well, you're really small. Look at you down there! You're like Smally McSmall. *beat* That's your name."
In Lilo & Stitch, Nani is almost hit by a car as she rushes back home and shouts at the driver, "Watch where you're going, stupidhead!" It comes back to bite her when said "stupidhead" turns out to be the social worker assigned to her. This is later used by Stitch against Gantu—as a sign of Character Development, no less, since such an insult is Lighter and Softer compared to his untranslated alien insults from the start of the movie that the Councilwoman finds so repulsive.
In Wrongfully Accused, Ryan Harrison gets into a shouting match with a guard on a prison bus that ultimately ends with a series of these types of insults.
Ryan: How dare you 'how dare me' when I how dare you, you big pee-pee head!
Guard: You're the pee-pee head!
Ryan: Mr. Booger Lips! Ca-ca mouth!
Same with Frank Drebin in The Naked Gun. Leslie Nielsen's dry, dramatic delivery made these sort of insults especially funny, it turns out.
Drebin: Now, now. I'm certain we can resolve this like the mature, rational adults we both are. Isn't that right, Mr. Poopie Pants?
Annie in Misery (book as well as film) typically uses insults of this nature. But when she doesn't..
In Kindergarten Cop, a kid named Zach is picked on by the other kids for being a quiet loner, calling him things like poo-poo head, poo-poo face and ca-ca poo-poo.
In Hook, Rufio falls prey to the "running out of things to say" variation when, after a long and creative volleying insult battle with Peter, he loses his composure and resorts to "You man! You stupid, stupid MAN!"
The aliens in Plan 9 from Outer Space try to reason with us Earth people by calling us "Stupid minds! Stupid, stupid!". That'll teach us!
In the first Survivors book, Lucky tries to distract the Fierce Dogs from his friends by insulting them. His two attempts are "Hey, stupid!" and "Mad dogs, sad dogs, stupid crazy bad dogs!" This doesn't work, and they only go after him after he starts insulting their mothers.
In an episode of Happy Endings, Jane and Max are fighting over a sweater which both claim to be theirs. Max maintains they are not going to do one of their dumb competitions-before running away with the sweater. Jane chases and tackles him, shouting "Get back here, you gay!" Max's response is "'You gay'? That's the best you could come up with?"
Will and Grace: when Ellen finds out that Grace once slept with her fiance Rob, she decides she has to sleep with Will to balance it out, despite his protests. When he tells her to stop and look at what she's doing, she flings herself on his bed in despair and declares herself to be a "dumb, stupid idiothead."
Bobo (trying and failing to read a letter): It says you're a dodo-head.
Observer: I'm the dodo-head? Why, of all the unmitigated gall! You're the dodo-head!
Peep Show: Mark, trying to get out of marrying Sophie, resolves to go over to someone and insult them, but can only think of saying "jizz-cock", which he laments is like calling someone a "piss-kidney" as a properly working cock would jizz. He nevertheless does it, and berates himself for not going with "arsehole" after the person he confronts calls him that.
Sheldon of The Big Bang Theory resorts to these kinds of insults when he doesn't have time to think of a good comeback, and will actually apologize for his "language" to whoever is there with him.
"Now, if you'll excuse me, I'm going to do work which promises significant results. As opposed to what you do, which... does not. Yeah, you heard me!"
If you poke around some Christian bookstores and church thrift shops, you can find T-shirts that proudly declare your sincere, deeply-held conviction that "Satan is a poo-poo head!" Also available on bumper stickers!
M. Bison: My soldiers are skilled, but I am supreme. Guy: Yea, a supreme fat-head!
Most of the trash talk in Team Fortress 2 is of this calibre. With the Spy, it's doubly hilarious because he says fratboy-level insults as if he's James Bond.
Monkey Island's Insult Swordfighting always give you the option to wittingly insult your opponent with "you're ugly!" and "you're stupid!". These insults automatically fail, with the only rebuttal being "is that the best you can come up with?".
And then there's Gyubrush's often used insult "You big old bed-wetting doody head."
Asura characters in Guild Wars 2 have been known to charge in to battle yelling "You're dumb! You'll die and you'll leave a dumb corpse!"
In Way of the Samurai 4, if you fight Kotobuki at the start of the game, and then confront him again in the evening after meeting with Akagi (who leads Kotobuki's enemies, the nationalist Disciples of Prajna faction), you can choose to call him and his lackeys "stupidheads".
The Inexplicable Adventures of Bob!. When Rocko gets rejected for a teaching job at an etiquette school, Molly says, "Aw, they're just a gaggle of poop-headed elitists! You're neat!"
In Everyday Heroes, when Greta Goode actually loses a video game (*gasp!*), she unleashes her fury on the victor ... which, at age 7, amounts to "You big stinkybutt!"
Elan in The Order of the Stick is prone to using insults like these. He's slightly better since he received expert training in the Bardic art of You Fight Like a Cow (hey, even lame puns are an improvement), though his insults outside of combat are as lame as ever.
The episode "Bots and the Bees" gives us this exchange between Bender and his son Ben:
Ben: Bend it, daddy! Bend it like it called you poo-poo face! Bender: It called me what?!
"The Birdbot of Ice-catraz":
Fry: Fine, I've got a toast. To Captain Bender, he's the best... at being a big jerk who's stupid and his big ugly face is as dumb as a butt!
In a The Real Ghostbusters Halloween Special, a monster named Boogaloo is terrorizing the city. Peter tries to get its attention. "Hey, Boogaloo! You're ugly and your mother dresses you funny!". For the record, Boogaloo is about a hundred feet tall, covered in multiple faces and tentacles, and not wearing any clothing at all. Nevertheless, it works.
Bubbles: (straining with all her reserve) I'm... not... gonna... cry... you... big... DOO-DOO BRAIN!!
In an episode of Recess, there's a scene where two first graders are arguing. One of them calls the other a loser, causing him to call the other a "Loser-more".
On Celebrity Deathmatch, in the fight between Simon Cowell and Ryan Seacrest, Seacrest can only come up with lame insults like "doodoo head" and "double doodoo head" in response to Cowell's epic burns.