Two beliefs about the significance of ordering anchovies as pizza toppings.
Jan Harold Brunvand, Too Good To Be True, rev. ed. (New York & London: W. W. Norton, 2014), 290.
I got another twist on pizza delivery in a letter from a reader in Australia. The writer had heard that the Goliath of the industry there (Guess who?) had an agreement with the city’s drug squad. Whenever a delivery person suspected that the people who had ordered pizza might be under the influence of drugs (“and especially if they ordered double anchovies”), then the driver would immediately notify local police to stage a raid.
Supposedly, in return for this reporting service, the pizza company’s drivers never received speeding tickets. Personally, I wouldn’t trust anyone who would order even a regular-size dose of anchovies on their pizza.
Moira Marsh, Practically Joking (Logan: Utah State University Press, 2015), 50-1.
A popular … practical joke is ordering pizzas by phone to be delivered to an unwitting target. Many pizza delivery businesses get two to three such orders every day, so employees are on the alert for bogus orders. “We’ve had our share of people ordering pizzas for nonexistent people or for people they don’t like,” one told me. “Weird-sounding orders are suspect.” “Hold the anchovies” is a frequent stock phrase in the American popular press whenever the pizza business is being talked about…. The perception is that the little salty fish are not a popular choice on pizzas in this country (although they may be more in favor in other countries)…. Accordingly, pizza company workers recognize that orders with anchovies are unusual, and therefore suspicious. More than once I was told, “If the order is fake, they order anchovies.”
This observation may be another example of the tendency to explain anomalies as fabrications. However, it is possible that practical jokers who phone in bogus orders do include the anchovies, even though this choice might tend to discredit the trick and cause the fabrication to fail. Some absurdity is necessary to ensure that the fabrication stays within the realm of play. If the absurd anchovies are present, the implied argument is that the targets should have recognized the trick; if they do not, the fault lies with them. While I do not have direct experience of people who phone in bogus pizza orders, this suggestion is based on observations from many other practical jokes.