Query: On what radio station did Kanye West deem himself "the biggest rockstar on the planet"?
Context: Later in 2013, West launched a tirade on Twitter directed at talk show host Jimmy Kimmel after his ABC program Jimmy Kimmel Live! ran a sketch on September 25 involving two children re-enacting West's recent interview with Zane Lowe for BBC Radio 1 in which he calls himself the biggest rock star on the planet. Kimmel reveals the following night that West called him to demand an apology shortly before taping.