Don't Be a Sucker (1947)

Hat-tip to Wil Weaton for finding this one. Wikipedia sez:

"Don't Be a Sucker!" is a short film produced by the US War Department in 1943 and re-released in 1947. It has anti-racist and anti-fascist themes. The film was made to make the case for the desegregation of the United States armed forces.

The sound skips a bit at the start, but this little flick is probably older than your parents, so it's excused. Still relevant.