The line comes from Dr. Seuss's The Lorax, first published as a children's book in 1971 and adapted into an animated film in 2012 where Danny DeVito voiced the Lorax. His role in the story is to protect the Truffula Trees and warn against cutting them down. Online, the short clip was shortened and shared as a standalone reaction sound, often with the final word clipped to tree in reposts. It stays popular because the protective stance translates easily to jokes about plants, parks, and the environment.