Stefán Karl announced in October 2016 that he had been diagnosed with bile duct cancer. On the same month, GoFundMe campaign was subsequently created by "LazyTown" head writer Mark Valenti to pay his living costs when he became too ill to work. The campaign was popularized by various YouTube users uploading parodies of Stefán Karl's work. This eventually made the songs "We Are Number One" and "The Mine Song" from "LazyTown" become Internet memes. In August 2017, Stefán Karl stated he was in remission. He clarified on his GoFundMe campaign that while his metastases had been removed after successful liver surgery in June 2017, he still had the disease and had refused further adjuvant therapy.