On this week's 30 Rock, Jack used an analogy about a company buying both a diarrhea-inducing corn chip manufacturer and a diarrhea medication to boost sales. The Sarah Silverman Program aired the same joke on Oct. 8th, 2008. Videos inside.
First, the scene from the 30 Rock episode, "Diversity":
Second, the scene from The Sarah Silverman Program, season 2, episode 7, entitled "High, It's Sarah":
Whether or not the 30 Rock writers knowingly copied The Sarah Silverman Program is unknown, but the jokes are awfully similar...
Thanks to the lovely Bette Bentley for noticing the similar jokes!