By our unofficial count, exactly one actor performed in a movie in blackface in 2008. Tropic Thunder may have seemed like just another wacky-brave escapade in the fascinating career of loony-tune genius Robert Downey Jr., but there was a method to this particular madness: Bobby D. was tracing a cursive line back to his pops subversive strain of anarchic comedy. You see, in the 60s and 70s, Robert Downey Sr. wrote and directed a quiver of clever and largely undisciplined (read: mightily stoned) movies satirizing social conventions. "Under the Underground: The Films of Robert Downey" concludes tonight with the messy bull-in-a-china-shop escapades No More Excuses (clocking in at just 44 hit-and-run minutes) and the ultrarare Moment to Moment (starring the comic dervish Elsie Downey, Pops wife and Juniors mother). Dont be shocked if someone dashes across the screen in blackface.