It seems Sun City resident Kay McConaughey was fated to play Tassie, the saucy citizen of a small East Texas town.

When Austin director Richard Linklater chose actual East Texans to play the townspeople who serve as a sort of Greek chorus in his dark comedy, "Bernie," he looked no further than a star's mom for one earthy role.

"Rick said: 'Hey Kmac, there's a part for you,'" she says, before explaining the spelling of her nickname. "'I can't imagine anyone else doing Tassie,' he said."

Matthew McConaughey's gregarious mom didn't take long to consider the director's offer.

"No, you are right, Rick," she recalls saying. "I can do that without even stretching."

She shares one of her scenes in "Bernie" — it opens in Austin, New York and Los Angeles theaters on Friday, after having premiered at the South by Southwest Film Festival — with her offspring. He plays the district attorney who prosecutes Jack Black's character for killing Shirley MacLaine's.

"He said: 'Hey Mom sit down, don't be nervous'," she recalls. "And so we started talking. It was easy."

Although she was born in New Jersey and attended college in Kentucky, McConaughey, 80, has lived in Texas since 1952.

"I'm a true Texan," says the former teacher. For 10 years, her family lived in Longview, where Matthew and one of his brothers, Patrick McConaughey, attended high school. Although Longview during the 1980s qualified as a rather large East Texas town, if not a small city, it bore some resemblance to nearby and much smaller Carthage, where Bernhardt "Bernie" Tiede confessed to killing the wealthy widow Marjorie Nugent, inspiring Skip Hollandsworth's Texas Monthly story, and the movie.

"Everybody knows what everybody else is doing," she says. "I knew what Matthew and Patrick were doing. And they'd better be where they said were going to be! It wasn't easy for them to get away with anything."

The closest urban temptation was more than 60 miles away.

"The only thing you could do is go to Shreveport," McConaughey says. "And what's in Shreveport?"

She's now well ensconced in the Georgetown retirement community she calls "Sin City," where she's lived since 1998. It helps that her son and his fiancée, Camila Alves, and their two children spend more time at their Austin home.

"I get to go out with them, when they ask, a couple times a month," she says. "I get to have fun with the kids. I'm glad they are here."

Matthew McConaughey proposed to Alves last year, but his mother can't share any details about the ceremony.

"I don't know anything about a wedding," his mother says "I just know I better be invited."

Her other sons, both in the booming pipeline business, live in Midland and Houston. All told, she has five grandchildren and three great-grandchildren.

After just one conversation, it's easy to guess where her son might have acquired his "Just Keep Livin' " motto.

"I honestly enjoy life," she says. "I don't hold a grudge. If I get mad, I do. But basically life is good. I make myself happy. We always have choices. They may not always be good choices, but I always take responsibility."

And that's the way she raised her kids.

"Stay responsible for your actions," she says. "And never lie. Once they lie to you, it's no good."

She gives some credit to their late dad, Jim McConaughey, the six-foot-three-inch tall former Green Bay Packer whom she divorced and remarried multiple times. "Big Jim" died in 1992 after marital relations, as his widow famously related in her book "I Amaze Myself!"

"The kids still talk about him," she says. "We tell Pop stories. We keep him alive without even trying."

Blonde, tan and trim, Kay McConaughey, who clearly takes care of herself, looks smashing.

"A lot of it comes from not stressing out," she says. "That will age you quicker than anything. People who think they are going to fix other people's problems. If you can't fix it, just drop it."

McConaughey shows no signs of slacking off.

"I want to live to be 97," she says. "I already figured it out. That way I can see Vida (a grandchild) graduate. They may have take me up there in a walker, but I'll get there."

Contact Michael Barnes at mbarnes@statesman.com