Pet Rocks were among the most popular gifts of 1975, and the name has become synonymous with ridiculous fads. Developed by Gary Dahl, a California advertising man who came up with the idea, the Pet Rock—actually rosarita beach stones that Dahl bought for one cent each and sold for two dollars wholesale—was a hit at an August 1975 San Francisco gift show. By Christmas of 1975, Dahl had sold two-and-a-half tons of Pet Rocks, or one million rocks, and had become a millionaire. The Pet Rock was packaged in a cardboard "pet" carrying case and came with the Pet Rock Training Manual. Dahl rocketed to fame, appearing on The Tonight Show twice. Immediately after Christmas 1975, the market for Pet Rocks dried up, and Dahl donated his remaining inventory of one hundred thousand to needy children a year later. Dahl's next attempt to sell nothing for something, the 1976 Official Sand Breeding Kit, was a flop.

Gary Dahl, creator of the Pet Rock, rings up $2 million in sales.