 The scene where Doyle and Russo chase down the dealer near the  beginning and Gene Hackman shouts out his famous question "Did you  ever pick your feet in Poughkeepsie?" is based on the real "good  cop/bad cop" interrogations of the real "French Connection"  detectives, Eddie Egan and Sonny Grasso according to William  Friedkin in the DVD Commentary. Grasso would gingerly ask a suspect  direct questions about his crimes to which Egan would alway but in  and yell out unusual questions like the Poughkeepsie question. The  suspect would get so rattled by Egans forceful questioning that he  felt more comfortable answering Grassos questions, thus  incriminating himself.