"We drank the night away, and then I had to go to a meeting with Steven Knight, our director, the next day, and I was just kinda -- have you guys ever had to go to a meeting hungover?" Hathaway asked the audience. "I was just kidna stumbling in with one eye open and I was trying to convince him about certain things about my character."
"And at the end of it I said, 'Listen, I have a confession. I was hungover the entire time.' And he just goes, "Oh, really? I couldn't tell,'" Hathaway continued. "Then two days later we had another meeting and I showed up and said, 'Oh, now I can tell.'"
Going into a business meeting hungover isn't the only reason the Oscar winner decided to give up the drink. Her 2-year-old son, Jonathan, played a big role in the decision.
"I quit drinking back in October, for 18 years. I’m going to stop drinking while my son is in my house just because I don’t totally love the way I do it and he’s getting to an age where he really does need me all the time in the mornings," Hathaway explained.
"I did one school run one day where I dropped him off at school, I wasn’t driving, but I was hungover and that was enough for me. I didn’t love that one," the actress added.
"Yeah. That's another reason I don't want kids," DeGeneres quipped.
Hathaway and husband Adam Shulman -- who tied the knot in 2012 -- welcomed their little boy in April 2016.
The actress' new steamy noir drama, Serenity, reunites her with McConaughey, who previously appeared alongside her in the 2014 sci-fi drama Interstellar. The film also stars Diane Lane, Jason Clarke and Djimon Hounsou, and hits theaters Jan. 25.