Elaine is consulting a rabbi, who offers her Snackwell's Cookies. He says he fears that knowing they're fat free may cause people to overindulge. Making them fat-free lowers the price of eating them; consumers respond by eating more.

Kramer has invested in a fat-free yogurt shop, but Jerry and Elaine begin to gain weight after indulging in it.

Jerry is getting a new air conditioning unit. Elaine asks why, because he's never wanted air conditioning before. But Jerry's new girlfriend feels more comfortable in with air conditioning, so Jerry is getting one—his demand has increased.

Elaine and her old boss find that selling just the tops of muffins is more profitable than selling the whole muffin (which consists of the top + the stump). So are the top and the stump complements or substitutes? Neither--the stumps are an economic bad, which reduce utility. Evidence for this is found in the fact that homeless people won't eat the stumps that the muffin-top restaurant throws away, unless they come with the tops as compensation.

Jerry is dating a girl but really wants to date her roommate. George suggests that the only way to make the switch is to propose a menage a trois to his current girlfriend, which will turn her off and her roommate on. Jerry follows through on George's plan, and finds that both girls are "into it." But Jerry can't follow through—and George can't believe it. To Jerry, the roommates are substitutes; to George, they are complements.