Mary-Beth says after the song "Louisiana Woman, Mississippi Man" that she had never been east of the Mississippi River, but after another song, she starts talking about belt buckles, and she says she "bought a huge one in Florida the size of a hubcap." This is most likely due to the idiotic culture of being a redneck.
After CJ begins to start missions with Catalina, Mary-Beth mentions about a rumor she heard about a young couple stealing across the state. It could be reference to CJ and Catalina stealing from stores across Red County.
Asides weather reports, Mary-Beth mentions comments about in-game story lines.