You may think that children are dummies who crave whatever toy they're told to by television advertisements. Well, discriminating children all over America have just made the hottest-selling toy on the market out of something that has yet to be advertised.

What they recognized about it is that:

1. It looks disgusting.

2. It feels worse.

3. It is seemingly hard to get out of clothes.

4. It is seemingly near impossible to get out of hair or carpets.

5. It has little or no function except that of offending others.

In other words, the perfect toy.

The name of this stuff is Slime, and you can hardly find it in area stores because it sells out a quickly as it comes in.

What it is a gel-like goo, 95 per cent water, an unpleasant green, of slippery consistency. It comes in a small green garbage can, retaling from $1.19 to $1.89.

It has no instructions - only a few disclaimers. "Keep it in its own can or it will dry up." "Sticks to rugs, fabrics and hair." "Dry cleaning will not remove."

Since it came on the market last spring, something like 7 million cans have been sold. Mattel, which also brought you Barbie and Baby Brother, was planning to advertise it, but can't now, because the supply s not now sufficient for even the word-of-mouth inspired demand.

"I decided not to buy it at first, because it can't be dry-cleaned," said Woodward & Lothrop toy buyer Kenneth Wong. (The company advises cleaning Slime stains with vinegar and water.) "But we did get some in, and sold 600 cans in five days. We could have sold more if we'd had it.

"Some people have been throwing it at each other. We had someone taste it. A customer who wanted to know what it tasted like. It's non-toxic. He said it wasn't the best tasting stuff in world, but he lived."

Hecht's is selling it "as fast as we can get it in," Sullivan's has sold a case every three days since the beginning of June. Garrison's calls it "the most requested item there is" and is eagerly waiting to get a supply.

Of course, adults are buying it - for themselves - as well as children.

"The secretaries of corporation presidents call me up," said Mattel spokesperson Joel Rubenstein. "They want one can, but they say they'll buy a case if they have to.

"I had some when I went to have a drink with someone the other day, and the bartender put it in a Marguerita glass and everybody wanted to know where they could get some. I know someone who took some as a hostess gift at a dinner party, and people spent the whole evening passing it around and talking about it.

"It's therapeutic. You can do whatever you want it - squish it, let it drip through your fingers, massage it, drop in on people's desks."

Yes, the ideal toy.