THE TOPPS Chewing Gum Co. is having a great success with its new "Garbage Pail Kids" trading cards. They feature such grotesque and mildly repugnant characters as Wacky Jackie, Greaser Greg and Wrinkled Rita (a garishly dressed matron posed with a poodle before a palm tree).

The huge popularity of the cards among children has alarmed some educators and parents, who see them as at best a distraction from schoolwork and at worst an unwholesome influence. Some of those who are alarmed are probably the same ones who say that children should be treated as real people, respected and listened to.

Listening is instructive. It could give you a clue as to why Garbage Pail Kids are selling so well. Eavesdrop on a group of 10-year-old boys and you may hear them converse intelligently on any number of subjects. Continue to listen, however, and you are likely to hear the conversation degenerate first into name-calling, then into giggling and finally into a competition to see who can best mimic the sounds produced by gastrointestinal distress.

Most of us don't quite know what to make of this tendency, but the Topps Chewing Gum Co. obviously does. It is making money with Dead Fred, Leaky Lindsey (her problem is a runny nose) and Disgustin' Justin. All of them appeal to that side of children which belches in class, laughs when the teacher drops her eyeglasses in the fish tank, and strives to produce the most disgusting description possible of its recent bout with the flu.

There's no telling how long the current trading card fad will last, but if you'd like to cut it short in your household, here's a suggestion: Get your children a nice leatherette album and tell them it's to keep their Garbage Pail Kids in. Tell them, "Here's a place for Dead Fred and here's the pae where you put Wrinkled Rita and so on. Now, I want you to be sure to paste in three of them every day after school." That's probably the last you'll ever see of the album -- or of Nasty Nick, Bony Joanie, Mad Mike and Wrinkled Rita.