Many of the Michael Gallagher/Tom Bunk one-page gags employ this, particularly with Bunk's over-the-top grotesque and gory artnote His other work included Art Shift-era Garbage Pail Kids, for what that may be worth. For instance:
A kid pops a zit and ends up swallowed by his own pus and gore.
As seen at Agony of the Feet, man buys magnetic insoles for his shoes which are so strong that they pull an entire shelf full of sharp knives down through his feet, followed by an entire refrigerator crushing him to death.
Rock music fans try to crash a concert by pushing a chain link fence down. However, the fence is so heavily reinforced that it just slices their bodies to smithereens instead.
A nurse is drawing blood from a patient, but gets distracted by a phone call. When she returns, the patient is dead and dried-out, and their IV bag is gushing blood.
The very first Mad story ever ends with a man walking away with his own severed head.
"I am... a VAMPIRE Batboy!"
An off-putting Fold-In, seen in #223 and the Mad Gross-Outs issue, sports the image of a lady whose right side is bare skeleton; the setup is "What is always the movie industry's ghastliest production?"Answer "The Oscar Award show!"
One of the mags had a back-panel illustration of a nuclear power station going into meltdown, with lava spewing from its cooling towers. In the foreground, a very worried Alfred says, "Yes...Me worry!"
The October 2018 edition of the magazine had a good dose of Realism-Induced Horror with "The Ghastlygun Tinies", an "update" on Edward Gorey's The Gashlycrumb Tinies. Instead of telling of kids dying in various ways, it says that kids only seem to die in one way nowadays: school shootings. The story tells more disturbing things happening during the shooting, ending on this note:
Z is for ZOE, who won't be the last.
And if recent trends have shown, the poem, and that particular line, are very accurate.
The animated series
"Toys 4 Bratz" is a little bit disturbing for a kid's show. Considering it shows BLOOD along with a girl getting cut by a Baby Cutz-A-Lot doll, a boy being electrocuted by a Lectroland Playset, and another boy who lost a finger to a Skill Saw.
The Supernatural parody scared some people a little, especially when the demon escapes from the girl's soul.
Ghost Rider's Training Wheels also has a demon in it.
The dolls melting in Flammable (the claymation parody of Katy Perry's "Firework" music video), is pretty creepy when you look at it.
A Mike Wartella cartoon, features a scene were a lady walks into the kitchen, minding her own business, when suddenly, the Grim Reaper appears from nowhere and then outright kills her.
The moment Bear Grylls gets beaten by Winnie the Pooh is a little unsettling, and fora fewgoodreasons.
The Cars parody with Lightning McQueen being slowly and graphically crushed while he pleads for his life.
The Modern Family / The Family Circus crossover sketch. Seems harmless enough...till the end where it's revealed Billy has been holding his cast hostage against their will and likewise does the same to the Modern Family cast by making them a part of his comic.
A deliberate one in which we see a giant rabbit pulling out carrots and picks one that has humans clinging onto it. The rabbit then proclaims that rabbits rule the world and makes a disturbing and horrifying face to the camera, afterwards.