From WENN.com

The Lincoln Lawyer star was out drinking when he bumped into the casting director for the cult coming-of-age movie, and they hit it off so much McConaughey signed on to play charismatic character David Wooderson.

He tells Total Film, ""I sat down and introduced myself. And a few hours later, we got kicked out for re-enacting holes on golf courses we had both played. At the end of the night he said, 'Have you ever done any acting?' I was in a beer commercial for about half a second. And he goes, 'Well, you might be right for this part for this movie...'""