The document discusses 6 advertising campaigns that were successful due to having a clever core idea. It provides examples such as the Mauka Mauka cricket meme ads in India and Kia's hamster car ads. The document advocates that ads should be entertaining but not too entertaining, as excessive entertainment can reduce persuasiveness. It also discusses how some campaigns used user engagement and participation, such as Oreo's daily cookie designs and Project Shiksha in India to educate children. The document concludes by discussing how some content providers strategically integrate ads to make them harder to skip or separate from the content people choose to watch.