In season 6 when Peggy and Hank have trouble regarding the wet dreams of the latter, they go to a nudist area to try and solve their marriage. Hank is uncomfortable at first but gets used to being naked with Peggy while cooking burgers until Becky and Mandy show up. Mandy snarks that Hank has the munchies due to cooking burgers early in the morning, and Becky wonders why the meat smells so good and not smelling like smoke. Hank tells them that it is propane cooking the meat cleanly, but Peggy is annoyed that Becky and Mandy are trying to distract them. Hank talks with the women about propane, which saddens Peggy since she thinks he is attracted to other women. Hank is actually interested in talking about propane, and he discusses propane with them for some time. Becky and Mandy are happy to learn about propane and even say they will convert their house boat to propane, exciting Hank. The two girls leave, and Peggy finds out that Hank is actually attracted to propane and not other women, showing that their marriage is not failing after all.
Later in season 13, Becky and Mandy see that Buck Strickland has a "we are green" sticker on his car, indicating that Buck is allegedly an environmentalist. Buck confirms, and the two girls simply leave until Buck tells them he is setting up a celebration for his carbon offsets.