Duane hates lawyers because of his divorce from his wife and how badly it's going and recommends to one of his callers that he kill his wife instead of divorce her.
During his show, Duane mentions he was his middle school's soccer teacher, this is reference to Eastbound & Down where Danny McBride, his voice actor's character has to become his middle school's PE Teacher.
He may be the GTA V equivalent to Richard Bastion, host of The Richard Bastion Show, a show on GTA IV's radio station, WKTT, as they both say "I ain't just a whistling dixie, because no one likes a whistler or a whistleblower!" It also seems that Blaine County Radio might also be the GTA V equivalent to WKTT, considering they're also right-wing talk-radio stations with hosts that mention the previously stated line.
Duane mentions on his radio show that he used to be a 5th grade soccer coach. He now says that it isn't even a real sport.