Explaining on Instagram: "In the 2008 satirical comedy “Tropic Thunder,” Robert Downey Jr. delivered one of the most daring and discussed performances of his career. He played Kirk Lazarus, an intense Australian method actor who undergoes a controversial “pigmentation alteration” surgery to play an African American sergeant in a Vietnam War epic. Downey Jr. stayed in character throughout the entire production, even famously recording the film’s DVD commentary while still using the voice of his c