In the mid-'70s, an unknown editor named Gary Dahl was talking with his friends, who were complaining about all the work involved in caring for pets—feeding them, walking them, cleaning up after them. Dahl kidded that he had a pet that never caused him any trouble—a pet rock.

Surprisingly, the joke started to take off. Dahl recruited two colleagues as investors, visited a building-supply store and bought a load of smooth Mexican beach stones at about a penny apiece. The Pet Rock hit the marketplace in time for Christmas 1975. In a matter of months, some 1.5 million rocks were sold. It was a craze to rival the Hula-Hoop. For a mere three dollars and 95 cents, a consumer could buy … a rock—a plain, ordinary, egg-shaped rock of the kind one could dig up in almost any backyard.

For a few frenzied months in 1975, more than a million consumers did, becoming the proud—if slightly abashed—owners of Pet Rocks, the fad that Newsweek later called "one of the most ridiculously successful marketing schemes ever." When Dahl died in March 2015, his New York Times obituary claimed "the concept of a 'pet' that required no actual work and no real commitment resonated with the self-indulgent '70s, and before long a cultural phenomenon was born."

Pet Rocks made Dahl a millionaire practically overnight, but despite the boon Pet Rocks brought him he came to regret his success. The Pet Rock craze went the way of all fads—it died out and was replaced by the next fad. After his sudden wealth, he went through three marriages, a law suit, and failed attempts to match his previous success. At one point he said, "Sometimes I look back and wonder if my life wouldn't have been simpler if I hadn't done it."

Possible Preaching Angles: (1) Success; Ambition; Achievement; Emptiness—all of the success in the world can't satisfy our heart's need for Jesus Christ. (2) Conformity; Worldliness—It's amazing how a silly fad—a Pet Rock—can take off and become a worldwide craze.