ET spoke with the award-winning actress at the show's premiere in NY on Wednesday.
Nicole Kidman asked the three-time Oscar-winning actress to be a part of the second season, and she instantly said, "Yes!"
ET's Lauren Zima was with Streep at the season two premiere in New York City on Wednesday, where she explained why she signed on to the project without knowing what her storyline would be.
"I said, 'Are you crazy? I'd love to be in it,'" Streep recalled of Kidman inviting her to join the cast. So what made her jump on board without knowing what her role would be?
"I believe in these girls, and that first season blew me away," Streep marveled. "Everything about it: the writing, the depth of the performances, the style, the music, the whole world. And I couldn't wait to see where it was going to go."
Streep joined the drama as Mary Louise Wright, the mother of Alexander Skarsgard's deceased Perry Wright, and mother-in-law of Kidman's Celeste Wright. While filming, photographers snapped photos of the ladies on set, with Reese Witherspoon's feisty character, Madeline, throwing an ice cream cone at Streep's Mary.
"I blew her off," joked Streep about Witherspoon's ice cream throw at her. "She just told me that it wasn't on the show; it's on the DVD extra."
Ever since Streep joined the HBO series, the rest of the cast has not stopped gushing about the iconic actress and how honored they are to work with her. So how does that make her feel?
"When I forget my lines, they go, 'Oh, she's not so great,'" she jokingly said with a look. "I don’t know. I feel so lucky and so old too. I've been around. That's part of it. They've grown up looking at my movies. They just made me feel great."
ET also caught up with Kidman on the red carpet, where she shared how she just "begged" Streep to join the cast.
"She's such a supporter of us," Kidman said of Streep. "She didn't read anything [in terms of the script]. She signed on not having read anything. ... [I'm] completely indebted to her because she brings her talent, she brings her legitimacy, she brings her kindness, and she supported us."
For more on season two of Big Little Lies, watch below. The second season premieres June 9 on HBO.
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