When art school dropout Ralph Shaffer was hired by American Greetings to illustrate greeting cards in 1964, the 23-year-old was tasked with depicting delicate flower petals and hopping bunny rabbits. Every now and then, presumably to break the monotony of sentimentality, Shaffer would draw the rabbits being hung by a noose.

These morbid doodles didn’t make it to store shelves. Rather than offer him psychological counseling, the company decided to redirect his energies toward an eccentric squad of talent dubbed Those Characters From Cleveland. The company subdivision was responsible for creating intellectual property like the Care Bears and Strawberry Shortcake. In the 1980s, it was also charged with designing a line of toys that parents would find appalling and boys would find irresistible: Madballs. By the end of 1986, more than 10 million of the decapitated grotesqueries would be sold.

Those numbers weren't surprising to anyone who had done a little market research. One of the few guarantees in the volatile toy industry is that boys love to be repulsed. Beginning with Slime in the 1970s—a gooey green gel that resembled infected snot—kids could always be relied upon to embrace things that would make most adults heave.

In 1985, Topps released the Garbage Pail Kids series of trading cards, a parody of the Cabbage Patch Kids featuring revolting characters. Their immediate success was noticed by American Greetings, which had cornered the cute market with Care Bears but had never tried to appeal to booger-loving boys on the other side of the toy aisle. Sensing an opportunity, Shaffer, artist James Groman, and the rest of the think tank conceived of a line of squishy rubber balls with ghastly faces and names like Slobulus, Deathbreath, and Swine Sucker. Instead of a two-dimensional illustration on a playing card, kids would have a tangible object to torment their parents with.

Madballs debuted in February 1986 with a retail price of $3.99 apiece. The balls flew off shelves, emptying displays at Toys"R"Us and capturing newspaper headlines that attempted to rationalize such purchases by asking psychologists why protruding eyeballs were a selling point.

“Children find gross toys fun because that’s sort of where they are developmentally,” Brenda Baker, a psychologist based in Michigan, told The Morning Call in 1987. “These toys aren’t gross to them. They’re fun and funny.”

Because of their irregular shape, Madballs didn’t offer much in the way of actual bouncing. Instead, they were collected and displayed like morbid little trophies or used to antagonize siblings and adults. One boy, 7-year-old Chris Herter of Detroit, told The Morning Call he enjoyed rolling them down the laundry chute of his house. His mother, Libby, referred to the spheres as “gawd-awful.”

Although the toys were popular, they weren’t always welcome. Several schools prohibited them from being taken into classrooms because they were a distraction. One Madball, dubbed “Crack Head” for having a fractured skull, was renamed “Bash Brain” due to concerns people might think the company was poking fun at the drug epidemic burdening communities.

By September 1986, AmToy—the division of American Greetings that made these playthings—had successfully expanded Madballs into licensing, including Trapper Keeper folders. Bright Ideas, Inc. said Madballs outsold their Miami Vice products when it came to educational supplies. Direct-to-video cartoons, comics, and other ancillary merchandising followed. AmToy even released a line of action figures: When squeezed, their heads would spring into the air. AmToy also conceived a line of Blurp Balls that would spew a projectile when triggered. Among the characters: Up-Chuck Yeager.

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Madballs remained a popular seller through 1988, at which point children began to tire of sculpted vomit and decaying plastic heads. The line fizzled out, and remained largely dormant until a 2006 revival by Art Asylum, a licensee heavily into pop culture nostalgia. Dubbed Sickballs, the revitalized line attempted to compound the ick factor by having bodily fluids ooze out of orifices when the balls were squeezed.

Since then, Madballs have undergone a series of relaunches. Just Play releases grab bags of the characters at regular intervals, and KidRobot recently issued a line of Madballs designed after horror movie icons like Jason Voorhees and Freddy Krueger. Gross-out nostalgia is alive, well, and still drooling.