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.
Tuco's "bastard" monologue when Blondie's turning him in. Also, when he throws a fit after Blondie misses a shot against the rope.
Tuco: When that rope tightens, you can feel the Devil bite your ass!
The scene where Tuco robs a store after making it look like he's haggling over the price of a gun.
"People say you were killed in Albuquerque." "And people talk bullsheet!"
This little exchange:
Tuco: [reading a note left by Angel Eyes] "See you soon...id..eed..."
Blondie: [snatches note] "...Idiots..." [looks at Tuco] It's for you.
"When you have to shoot, shoot, don't talk."
The Overly Long List of crimes Tuco is accused of every time he's being hung. It seems to get longer and more ridiculous each time.
Tuco gives a threatening one-liner, eats the proffered cigarillo(!), and laughs evilly. Smash Cut to him rolling his eyes, back in the noose.
Tuco takes a horse and rides off to find the money while Blondie comforts a dying soldier. Once that task is complete, and while the signature riff plays, Blondie slowly lowers his cigar to the fuse of a nearby cannon and blows Tuco off his horse. Just the casual way he does it...