Instant Courtesy (S05E13)

Feeling Darrin has been rude to her, Endora resolves to teach him a lesson. She casts a spell, making him a perfect gentleman. Darrin's sudden gallantry at the office arouses everyone's suspicions. Mrs. Sebastian, a leading cosmetics manufacturer, is won over by Darrin's flattery, but Traynor, her advertising manager, is unmoved. As they argue, Darrin annoys Traynor by helping Miss Springer exchange a type-writer ribbon. Feeling they've lost the account, Larry advises Darrin to take a vacation -- for a year or two! At home, struck by Darrin's behavior, Samantha suddenly knows her mother is responsible. Mrs. Sebastian, who enjoyed being treated like a lady instead of a businesswoman, offers to set Darrin up in his own agency. Samantha zaps Larry into admitting he was wrong to fire Darrin. Bored with the whole thing by now, Endora removes her spell. Larry apologizes but Darrin feels its just to save the account. Mrs. Sebastian too feels it is just a selling tick. She withdraws her offer but Samantha zaps her into changing her mind again. Larry leaves to celebrate their success. Alone with Samantha, Darrin can't admit that they owe it all to Endora. (iTunes)