One of the best visual jokes involves Tuco and Blondie who, disguised as Confederates, spot an approaching army riding towards them. Noticing their grey uniforms, Tuco starts cheering for the South and spouting curses at the Yankees... until the soldiers come closer and start to shake the grey dust of the desert out of their blue uniforms.
Tuco: God's on our side because he hates the Yanks too!
Blondie: God's not on our side because he hates idiots also.