S6, E8: On his mother's urging, Franklin curbs his use of the word "stupid" when he gets mad. But old habits die hard and Franklin has an outburst in front of his impressionable sister. Now Harriet's saying the forbidden word and enjoying the reaction she gets every time she utters it. Franklin tries desperately to conceal from his parents the new word he's taught his little sister. / Franklin and Bear have a hard time convincing their friends that they've seen a sea serpent in Woodland Pond. After realizing it was just a floating toy they saw, the boys feel too silly to admit it to their friends and fabricate evidence to support their bogus story. Little do they know that their friends are already wise to their shenanigans.