How can public health organizations compete against the marketing strength of better-funded rivals like cigarette companies? One way to combat this inequality is to transform a weakness into a strength: by making a rival’s message act as a trigger for your own.

A famous antismoking campaign, for example, spoofed Marlboro’s iconic ads by captioning a picture of one Marlboro cowboy talking to another with the words: “Bob, I’ve got emphysema.” So whenever people see a Marlboro ad, it triggers them to think about the antismoking message.

Researchers call this strategy the poison parasite because it slyly injects “poinson” (your message) into a rival’s message by making it a trigger for your own.

-Contagious, p.84