The AmToy division of American Greetings Corp., which makes the toy, believes that gross is what young boys want more than anything. "The weird and wacky have always had some appeal to boys," says Jack Chojnacki, copresident of Those Characters From Cleveland, another division of American Greetings. It designed Madballs.

As with any new product, painstaking prepara- tions and rigorous research are behind the national rollout of Madballs. Boys were recruited to test three types of Madballs - choices that Chojnacki soberly describes as "scary, gross and humorous." It was simple to narrow the field, he explains: "We found gross was where it's at."

Chojnakci hastens to draw a distinction between Madballs and another entry in the gross-novelty market - the Garbage Pail Kids line of Topps bubble-gum cards. Those 25-cent packets feature a bag lady, acne sufferer, murder victim, juvenile delinquent and two-headed girl.