It looks like IMDB deleted it, but there's a Sammy Davis Jr. World War 2 movie from around 1970, where he plays an infrantryman caught-up in a German espionage-plot. Davis' unit is infiltrated with a spy, who's systematically murdering the team.
Davis isn't sure who it is, but he accidentally pisses-off a teammate who reacts by calling him a 'Niger', like the River (or German-pronunciation of the 'N-word').
Davis machineguns the guy, yelling: " Nyjer?!! It's Ni*************er!!!!! " And the movie ends.
It's a pretty powerful scene, that sort of trumps Jim Brown in Dirty Dozen and Carl Weathers in Force 10 From Navarone.