"Alright alright alright" is the catchphrase most associated with Matthew McConaughey. In fact, they were the very first lines he ever uttered in a movie.

As most Matthew McConaughey fans will know, the actor burst onto the screen and into our lives in the movie 'Dazed and Confused'.

Promoting his new memoir 'Greenlights' last night, the Oscar winner appeared on 'The Late Late Show'.

During the interview, Ryan Tubridy asked him abut where the catchphrase came from.

McConaughey said: "That phrase follows me or precedes me where ever I go. And people go, 'Does that ever annoy you?' And I say no, and let me tell you why, those are the first three words I ever said on film. In a little summer job on a film called 'Dazed and Confused' in 1992."

"At that time, I didn't know if that was the only time I'd ever be in front of a camera in my life," the actor continued. "I didn't know if it was going to be just a little three-day hobby and I'd never be in front of a camera again. 28 years later, here we are. It's turned out to be a career."

He talked about how his character Wooderson in 'Dazed and Confused' originally only had three lines in the entire script. One night, he was visiting the set and doing a wardrobe and makeup test when the director, Richard Linklater, came up with a scene in which Wooderson drives up next to a girl and tries to pick her up.

There was no script for the scene and it was his first time ever in a movie. So naturally McConaughey felt nervous and anxious.

"But I'm going over in my head, 'Who is my man? I'm Wooderson, so what is Wooderson about?' And I'm going well Wooderson is about his car, and I'm like boom, look at this. I'm in my '70s Chevelle. There's one. And then I'm like Wooderson likes to get high. Well Slater's riding shotgun, he's always got a doobie rolled up. There's two.

"Wooderson's about rock'n'roll. And I got Ted Nugent "Strangehold" in the 8-track, I'm listening to that. There's three. And then all of a sudden I hear 'Action!' And I say to myself 'Wooderson is about picking up chicks.' And in my mind, as I put it in drive, 'Well I got three out of four and I'm going to get the fourth - Alright alright alright.'"

Matthew McConaughey's ad libbing method hasn't always been foolproof though.

He also appeared on 'The Graham Norton Show' last night and told a story about working on the film 'Scorpion Spring' which went a bit wrong.