Watching the Sanderson family slowly falling apart over the course of the main story is pretty sad. Then, after finding one hidden toy receipt too many, Mrs. Sanderson finally reaches her breaking point and locks herself in her room. She then, through Chibi-Robo, gives the rest of her family a letter in which he criticizes not only her husband, but also Jenny and Tao (who are visibly hurt by her comments). What really drives the scene home is the last line of the letter:
Jenny: (looking completely devastated) ...Ribbit?