Reverse psychology is a powerful persuasion technique. Case in point: Visit Oslo’s tourism ad, which tells people they shouldn’t come to the Norwegian capital. Laced with irony, the spot features an Oslo native who questions if his hometown is even a city, given its small size and accessibility compared to tourist-packed metropolises like Paris and New York. Visit Oslo’s viral ad struck a chord in a season of protests and government crackdowns against over-tourism in popular destinations such as Barcelona and Venice. A low-key, unpretentious getaway like Oslo might be…