Is there a scam going around where a 'detective' calls you and says because you gave your phone # to a minor, you have to pay a fine?

I had a detective contact me by phone a few days ago claiming I had given my number to a 13 year old girl on the chat site mbuzzy. If I did it was a mistake, as I do not talk to minors. Of course he claims it was an undercover detective anyway. Anyway, the guy had absolutely no info about me personally, including he never addressed me by name. The outcome today was when he called back he said I had to turn myself into a sheriff, then stated he was just kidding that instead I have to pay a $150 fine. The number he gave me to contact is a 215 area code which the number I believe is a cell phone. Any clue what's going on?