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Watch out, synthetic marijuana pushers of the District—-Mayor Vince Gray is on your case. The mayor took to the streets of Petworth this afternoon to convince stores not to sell the drug that the Department of Health says will turn users into zombies.

The tour—which is becoming something of an annual affair for the mayor—got off to a rough start, when the first cashier Gray confronted claimed that he didn’t speak much English. Not only did the clerk not know what synthetic marijuana was, he didn’t even know what regular ol’ marijuana was.

Gray wasn’t buying it. After showing the cashier that everyone else in the room was familiar with the concept of pot, he told him to bring over the store’s license. “Knew what I was talking about when I ask for a business license, huh?” the mayor deadpanned. (The routine looked a little tacky to LL, especially after the cashier told reporters that English is his second language, after Amharic.)

Later, Gray defended his skepticism about the man’s language skills. The mayor claimed that a person on the street told him that the store did sell synthetic marijuana, information Gray said “would raise questions about the language issue.”

The investigation went better at another shop, where the mayor confiscated a marijuana grinder adorned with Bob Marley‘s face. He also discovered two boxes of rolling papers at a gas station. (For stores that don’t generate at least 25 percent of their revenue selling loose tobacco, the papers are illegal.) The illicit smoking supplies will be turned over the Department of Consumer and Regulatory Affairs.

While no synthetic marijuana was found, Gray asked cashiers to fill out a form promising they wouldn’t carry any. Among the 10 businesses that signed on, Gray received promises from a dry cleaner, two restaurants, and a nail salon—-places LL doubts needed much convincing to not sell “spice” in the first place. Business owners will receive framed copy of their pledge not to sell the drug.

After a drug paraphernalia-free tour of a Yes! Organic Market on Georgia Avenue NW, Gray explained that his visits were meant to stress the importance of not carrying the drug.

Nadine J. Parker, the Wards 3 and 4 director with the District of Columbia Prevention Center, had a more visceral explanation. The businesses should be just as concerned as the mayor is, Parker explained, because of what kids on synthetic marijuana will do.

“They’re going to go into the stores and rob these places,” Parker says.

Photo by Will Sommer