The WhatsApp groups have one simple rule: typing and speaking are forbidden, on pain of immediate removal. Only voice notes with whistling are allowed, although the choice of content is up to the sender: it can be an imitation of a bird or a tune such as the theme from The Pink Panther or the introduction to Scorpions’ Wind of Change . In recent days, Brazil has seen a sudden craze for whistling-only WhatsApp groups, bringing together people of different ages and professions, including members of Congress . Some of the groups get up to 600 voice notes a day, with the most popular performances racking up hundreds of thousands of views on TikTok, such as interpretations of Evanescence’s Bring Me to Life or Gorillaz’s Feel Good Inc. New groups are emerging every day in the world’s second-largest WhatsApp market, some reaching the 1,024-member limit in less than 24 hours, prompting administrators to create a new one and repeat the cycle.…