Ben Stiller first conceived the idea for Tropic Thunder while working on the Steven Spielberg World War II drama Empire of the Sun in 1987. At the time, many of Stiller’s colleagues were in boot camps training for roles in war movies and would talk about their experiences as if they were actually in the military. “This sort of self-important, self-involved thing seemed funny to me,” he recalled following Tropic Thunder’s 2008 release. Twenty yea…