"Hey look man, joint stains," said the curly little 15-year-old kid, holding up two browny-yellow smudged-up fingers. Everyone laughed. The kid laughed too, then lit up again.

The twisted paper at the end burned very fast at first. There was a little flame at the end. But when the fire got to the marijuana, it slowed down. The kid took a very deep drag, swallowed the smoke very hard. His face lit up. He threw out his arms and threw back his head. "Man, this is a groove."

And it was.

Three or four hundred young people were smoking pot on the Boston Common a week ago Sunday. And just as many did it again the day before yesterday. No one was arrested. There wasn't a cop in sight most of the afternoon. There it was--evening's empire returning into sand right in the middle of the Hub.

A good number of them were trying grass for the first time. Like one pudgy, freckly-faced little girl who told the mustachioed kid who was handing her a joint, "God, I was pretty goddammed freaked out there for a second. But it feels great now."

At the first of these affairs (which some callous person called a Smoke-In), everyone was sitting around on the grass, clustered in groups of 50 to 100 and looking very euphoric. They were quite thoroughly friendly. Everyone was passing a joint to his neighbor sitting squat-legged next to him. Very warm and communal and all.

They were young. Most were under 20, although there were some mommies and daddies carrying babies around on their shoulders, all inhaling the heavy bittersweet burning smell. People were playing guitars and bells and tambourines and singing. The whole atmosphere was grassed.

And about the police--they stayed away. A spokesman said that night that no one had been arrested "because no one was smoking pot." Pressed by a reporter about how they knew, the officer mumbled something about not wanting to cause a lot of unnecessary trouble by searching everyone.

But there was marijuana being smoked on the Common.

One fellow flipped open a flip-top box of Marlboros, offering the 20 carefully rolled joints inside it to a reporter. "Here, take one. It's free. We've got at least 2000 joints out here. Some guys are just going around waving big bags of grass. Wild, you know?"

And it was marijuana after all. It smelled like it, tasted like it, worked like it. No one who smoked any doubted that for a second. But no one was busted.

Last Sunday there were signs posted all around the Common reading: "Walking, Standing, Or Sitting Upon The Grass Is Prohibited. Revised ordinance, chapter 29, section 85." But people--hundreds of them--were walking, standing, or sitting upon the grass. No one was arrested, no one reprimanded.

By the way, that same Sunday, Cambridge police were rounding up 18 people in a huge drug raid. The apartment had been under surveilance for three weeks.

Even more surprising than the police inaction those Sundays was the way the press ignored the whole event. The Boston Globe did not carry the story at all last week. "There was no Smoke-In," one Newthinking City Deskman said. The Herald Traveler did say that 3000 young people had gathered on the Common, but it was not certain that marijuana was being smoked.

If there is some sort of conspiracy of silence going on here, the police and the mass media seem to have gotten the idea from New York. There, hundreds of hippies marched around Times Square into Grand Central Station, cops following them with prods of "Keep moving." Then they all hopped onto the IRT, riding downtown with newsreel cameras whirling in the subway with them. The newspapers said nothing. No one was arrested. The the East Village Other said: