If you have ever watched a Quentin Tarantino film and thought all that cursing and swearing was made up by the actors on the fly, think again.
At a press event for the director's latest movie, The Hateful Eight, the cast members reveal that the exacting film-maker hates it when they change his dialogue, even if it is just a single word.
The notable exception to this rule is Samuel L. Jackson, the star of Tarantino hits such as Django Unchained (2012) and Pulp Fiction (1994). He is one of the few performers allowed to alter the film-maker's scripts, which have won two Oscars.
When the two sit down to talk to The Straits Times in Los Angeles, Jackson - who is winning rave reviews for his portrayal of a bounty hunter in the film - at first denies that he gets any special leeway. The 67-year-old says he actually has a lot less work to do when handed a Tarantino script.
This is because the film-maker has typically worked out an exhaustive backstory for his character, says Jackson, who in 2011 was named the highest-grossing actor of all time, although he has since ceded that title to Stars Wars actor Harrison Ford.
With other movies, "half the time I'm sitting at home writing this stuff for myself - where I'm born, where I came from, what I did, what all my goals are - but Quentin's already done all of that".
Interjecting, the director says that Jackson does indeed get away with tweaking his dialogue and it is because "Sam is actually a very good writer, particularly when it comes to the characters and scenarios".
"And I rarely say that about actors because improvising usually isn't writing - improvising usually is adding curse words to the script that's already there and adding 'ums' and 'aahs'.
"It's because everyone's trying to be like Jimmy Stewart and make it more naturalistic, or they're just too f*****g lazy to learn the dialogue in the first place, so they just paraphrase to that effect.
But Jackson never "wings" it, Tarantino adds.
"He's actually come up with this days, if not weeks or months, in advance, and is thinking this would be a good element to put in the piece. So when he does it at rehearsal, it's actually a performance."
Thus when Jackson improvised a line in Django Unchained - a film that, like The Hateful Eight, is set in the years following the American Civil War - "he picked exactly the right words, he didn't overdo it and it brought us to our knees, it was so funny. He had worked it out to a fare-thee-well".
If he nixes one of Jackson's suggestions, the actor does not "hold a grudge for the rest of the day", Tarantino says.
The actor - who is married to actress and television producer LaTanya Richardson, 66, and has a 33-year-old daughter - maintains that the director is always receptive to good ideas.
"He allows us to rehearse in a very genuine way because he understands the value of rehearsal - that he learns a lot listening to us saying these words to one another and, once we get up on our feet, he learns what our relationship is to one another, who's strong, who's weak, what he needs to fix.
"I may go home and say, 'I like this speech, but I need to move this sentence here, and this there', and I'll come back and talk to him about it. And he'll say, 'Well, let me hear it that way.'
"Sometimes he'll go, 'It sounds better the other way', and sometimes he'll go, 'Oh yeah that's right!' Which is great," says Jackson, who plays Nick Fury in The Avengers and Iron Man movies and has also appeared in action hits such as Snakes On A Plane (2006) and Unbreakable (2000).
"We always come to some agreement that makes that character richer. And for me, I can look in the mirror and know the guy's supposed to say these things."