"My husband says, 'What Joan walk? You've always walked that way!'"

The quote is likely referring to a situation in which Joan has been strolling in a particular way for a long time, and her hubby has actually observed it. He is teasing her by asking if she has actually altered her walking style, suggesting that she has not. The quote could also be interpreted as a reminder to Joan that her hubby has always been aware of her routines and quirks, which he is focusing on her. It could also be translated as a sign of affection, as her other half is teasing her in a playful method. In general, the quote is likely implied to be a lighthearted tip of the bond in between Joan and her other half.