*Showtime’s new original series “The Big C” co-stars Gabourey Sidibe as the headstrong high school student of a teacher whose cancer diagnosis inspires her to finally start living life on her own terms.

Sidibe came to the role hot off of her Academy Award nomination for “Precious” and the whirlwind of across-the-board praise that surrounded it.

By now, everyone knows her story. The Brooklyn native skipped a college class to audition for the film, booked the lead role, and as Oprah Winfrey said at the Oscars, she’s suddenly found herself in a best actress category alongside Meryl Streep.

“Being an actress wasn’t a plan at all, and so it’s very strange what’s happened to me,” Sidibe told TV critics at a recent panel for “The Big C” in Los Angeles.

“I ride the bus and all of that. I’m very normal. But it’s the people around me,” she says, that have changed. “Like, when I go to a restaurant and I walk past, and everyone is like (waves hands in the air). That’s always really funny. It’s strange. I mean, it just goes to show that whatever plan you have for your life, you are wrong a lot of times.

Such is the lesson for “The C Word’s” Cathy, played by star Laura Linney. In the pilot, premiering Monday at 10:30 p.m., Cathy is already diagnosed with melanoma and is keeping it a secret from everyone, including her husband Paul (Oliver Platt), son Adam (Gabriel Basso) and green-living brother Sean (John Benjamin Hickey).

When Sidibe’s Andrea strolls into class late one day with a smart-ass remark, Cathy responds with a comment about her obesity, which later leads to a financial arrangement: Andrea accepts Cathy’s offer of $100 for every pound she loses.

Aware that her time is limited, Cathy apparently can’t stand to watch someone so young throw away hers – one artery-clogging potato chip at a time.

Sidibe has said that she is perfectly content with her plus size. In fact, the overall theme of “The Big C” – living every second of your life without compromise – is something the Brooklyn native has embraced for a long time.

“I kind of do things that make me happy anyway,” she says. “I’m a selfish liver, I guess. But certainly, I do know people who have both died and have survived cancer and [‘The Big C’] makes me think of them more.

“But my character doesn’t know about Cathy’s diagnosis at all, and so I wonder how many people in my life I don’t know about who are suffering.”

In the clip below, Cathy introduces Andrea to her brother.