After the show, Jack calls a meeting in his dressing room to ask the cast and crew not to make so many mistakes. They point out that he, too, made mistakes on the show; for example, he kept scratching his arm. Don does the State Farm commercial over again to ask Jack where he could have possibly made a mistake; Jack points out that this week they were on for General Foods. Jack decides he has been scratching his arm because of a skin allergy, and visits several allergists. He eventually discovers that he is allergic to Dennis. (thetvdb.com)