Matthew McConaughey was a 23-year-old unknown when he was cast as David Wooderson, the older guy who still hangs out with high school kids and picks up teenage girls, in Richard Linklater’s cult 70’s-nostalgia hit Dazed and Confused. The role of Wooderson was supposed to be a bit part, while the role of hippie stoner Kevin Pickford, played by Shawn Andrews, was supposed to be quite prominent.
But a combination of factors caused Linklater to minimize the role of Pickford, and expand that of Wooderson. Andrews, it seemed, had behavioral issues and couldn’t get along with just about anyone in the film’s ensemble cast; Pickford was supposed to be the best friend of lead character Randy “Pink” Floyd, played by Jason London, but London, like everyone else, couldn’t stand Andrews, and Linklater at one point needed to break up an actual fistfight between the two on set. If you watch the film, you’ll notice that even in scenes in which they appear together, they barely speak to one another.
McConaughey, meanwhile, was highly entertaining and charming in his delivery of the few lines Wooderson originally had, and as a bonus, got along swimmingly with the entire cast. So Linklater wrote more dialogue for the character on the spot, and had McConaughey improvise in other scenes, in order to give him more screen time and make Wooderson a bigger character, while Andrews’ screen time was cut (as was that of Milla Jovovich, who played Pickford’s girlfriend Michelle, simply because all of her scenes were shared with him).
So Matthew McConaughey basically Matthew McConaughey-ed his way to a bigger role. It was the performance that first gained him wide notice, and it gifted the world Wooderson’s trademark drawled catchphrase, “alright, alright, alright”.
McConaughey and London as Wooderson and Pink:
EDIT: for clarity, Shawn Andrews as Pickford: