NY- An undercover police officer got an unusual surprise during a prostitution sting.

Police said the officer was approached by Lisa Greene, 31, [pictured right] on Lodi Street. She got into his car, they drove to an alley and negotiated a deal.

But it was the woman who initially tried to make an arrest after asking if he was a cop. When he said no, police said she tried to handcuff the officer, and even used a radio to call for backup. That's when the police officer arrested her.

The woman on the other end of the radio, Elena Erwin, 20, was found in a nearby car and arrested.

Both women have been charged with criminal impersonation and conspiracy. Police believe the pair acted as cops as a scheme to try to get money from men who think they've been caught.