Description: An undercover sting by the New York Police Department and the city's Special Narcotics Prosecutor has revealed a booming business for drug dealers who now openly advertise on Craigslist. Police arrested 21 in the New York area after undercover officers made 63 separate drug purchases, responding to brazen ads for "bundles of dope" and open advertisements for Adderall, Xanax, or Oxycontin. One ad offered, "Friendly Nyu student who can offer pain relief and anxiety relief. easy, non-sketchy, straightforward meeting." "That's really what stands out in this case: the openness, the blatant approach," NYPD Police Commissioner Ray Kelly told ABC News. "The wording was such that you knew it was illegal, we knew the drugs we were talking about." Kelly said he has seen the number of prescriptions for Adderall and Oxycontin both skyrocket, with each going up by 100 percent over a four-year period. "Clearly there has been a major increase in the use of prescription drugs and clearly the use of illegal prescription drugs," he said. Kelley is helping to lead the national fight against the illegal drug trade online. Last year, the NYPD made a separate similar bust that netted 40 arrests. Those arrested included a financial advisor, a veteran photographer, and a graduate student at New York University.