The film's name
I wonder if Leone heard someone say 'Duck you *ucker' and mistakenly thought it was 'sucker' and a popular phrase?
shareRegardless of whether he thought it was sucker of *beep* I think Leone just had a brainstorm and imagined the title up as a popular phrase. Or maybe he saw some blaxploitation film and got his wires crossed.
shareTo be honest, Leone's title was 'giù la testa!', literally 'head down' - in italian it's not far from 'duck' or 'take cover' in a miltary-ish slang.
In itself, the italian cry had a bit of desperation - it's not just an order, more a 'keep your head down, you fool, for god's sake'
When the production translated and adapted the movie for the american market, they added the insult - and I may figure out that 'sucker' will sound offensive enough but was clean enough to be on the posters and flyers.
In the DVD Chris Frayling recounts how Bogdanovich protested at the name "Duck, You Sucker" but Leone insisted that Americans commonly used that exact phrase.
shareIt must mean something like keep out of trouble, run away when the game gets rough
And that is exactly what Sean/John Mallory has done ever since shooting his friend. But like Rick (Casablanca) - who sticks his head out for nobody - he finds out that no matter how big the forest, you can only run to the middle of it. After that you will run out of it again.