The D.C. police call it Operation Oregano Scam. The customers who buy the concoction of oregano, celery flakes and birdseed call it a ripoff.

In yet another in a series of increasingly bold efforts by police to disrupt illicit drug traffic in the city, undercover officers last week posed as drug dealers at 15th and Chapin streets NW, long a center for reputedly high quality marijuana, selling authentic-looking $5 packets of phony pot to gullible buyers.

Their objective to give Chapin Street a bad name and drive the buyers away.

"We've been selling oregano on Chapin Street to discredit the dealers up there," said Lt. Ron Harvey, head of the police 3rd District drug enforcement branch. "They have been selling a good grade of marijuana and they have a good reputation for good marijuana. We want to ruin that reputation."

Operation Oregano Scam is part of an ongoing, citywide crackdown on illicit drug activity that has included sweeping arrests of more than 200 suspected drug traffickers since mid-August, the use of video cameras and water trucks to intimidate and disrupt buyers and sellers on the street and even an undercover officer wearing a Schlitz bull costume to make surprise arrests.

With Operation Oregano Scam, police said the object is not to make arrests but simply to disrupt.

Last Thursday afternoon, four undercover officers dressed in appropriately casual street clothes stationed themselves at the Chapin-15th Street junction adjacent to Meridian Hill Park. Several regular dealers on the street, who recognized the four as police when they arrived in a marked cruiser, withdrew.

A steady procession of cars slowly cruised by, stopping long enough for their occupants to barter quickly with the men at the curb selling what appeared to be the standard $5 packets of marijuana. Many were to return minutes later, angry at discovering they had been had, but helpless to do anything about it.

Two women in an orange Vega with D.C. tags slowed as they saw the four men enthusiastically waving their right hands, which held small brown packages. They stopped and inspected each man's wares and settled for the packet held by Det. Robert Thompson. Officer Bobby White, who had been rejected, yelled over to Thompson, "Hey, tell them my stuff is just as good as yours," and he laughed with delight.

Within five minutes, the women were back looking for what one of them angrily called "that ugly boy who sold me this stuff." They gave up after three trips around the block. Thompson had decided to sit out the confrontation by resting behind a wall in Meridian Hill Park.

Most of the dissatisfied customers left after brief conversations with the phony dealers, some squealing their tires and shouting curses.

One man in a light-colored Cutlass Supreme was more unhappy than most. Moments after buying his "nickel bag," he rapidly backed his car up a block against the one-way traffic on 15th Street, pulling in next to the dealers. Leaping from his car, he shouted that he wanted his money back.

Officer Elliott Carter remembered the conversation this way:

Customer: "I want my money back."

Carter: "No money back, man."

Customer: "Give me my money back!"

Carter: "We can't. We're the police, man."

Customer: "I don't care. I want my money back."

The four officers then gathered around the man. Officer White held up his police identification, which the man carefully inspected. When he didn't appear convinced, two back-up officers in a nearby truck charged across the street and persuaded the man to leave.

Customer: "It's unfair. It's just unfair."

The customer got back into his car, and with hard stares for all, drove off down Chapin Street.

The bogus marijuana was made from a recipe devised by Officer John Eisel.

"First I went to the Giant and bought all the herbs that looked right," said Eisel. "I spent about $50 on oregano, tea leaves, parsley and celery flakes. We mixed it up in a big box, but it didn't look right, so we added some mud. Then we decided that the oregano was too strong, so we added some vanilla extract. Then it smelled like vanilla. Then we added in some bird seed and mixed it all up again. We packed about 300 bags."

So authentic was their ruse that two of the four police "dealers" were nearly arrested by two U.S. Park Police officers driving by. The park officers, who normally help patrol nearby Meridian Hill Park, jumped from their cruiser, pinned the two D.C. plainclothesmen to a brick wall and held them briefly until the undercover officers were able to identify themselves.

As for the $100 the undercover men received for selling the "nickel" bags of phony pot Thursday, it is listed in police records as suspected proceeds of a crime and will go into the city's general treasury, officers said. CAPTION: Pictures 1 through 3, Posing as marijuana dealers, Officers Eric (Speed) Hayes and Bobby White talk to customers on 15th Street NW. They were offering a special concoction of oregano, bird seed, parsley, tea leaves, celery flakes and mud. Their "ill-gotten gains," totaled $100. Left-over "nickel" bags. By Linda Wheeler -- The Washington Post