Leslie Mann Gives the Most Honest and Hilarious Advice to Daughter Maude Apatow

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When we say that Leslie Mann isn't like a regular mom, she's a cool mom, we actually mean it.

The How to Be Single star's daughter, Maude Apatow, is an actress in her own right, having appeared on Girls and in the Sundance film, Other People. So, what advice does Leslie give Maude that she wishes she had gotten at her age?

"This is going to sound weird," Leslie told ET with a laugh during a round table conversation with her co-stars. "But at 18, she's an adult, and she has like, the cutest body. You know, I tell her that she should just…show her boobs!"

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"Go out in public, and take off your clothes!" Dakota Johnson chimed in.

"It really doesn't stay like that forever," Leslie added, before joking, "I told Dakota this too, and she took my advice and did Fifty Shades of Grey."

Dakota received some equally wise advice from her famous mom, Melanie Griffith. "She always said not to compromise myself or my work or my dreams for anyone," Dakota, who is currently dating musician Matthew Hitt, revealed. "Especially a dude."

Meanwhile, Rebel Wilson had some advice to share about how to -- almost -- pick up Justin Bieber at a concert. The funny lady recently posted on Instagram that she and pal Kelly Osbourne tried to convince the “Sorry” singer to take them out after J.Lo’s Vegas show.

“We write him a note, a love letter. Because who else does that these days?” Rebel told us. “It was like grade school. I wrote him a letter, ‘Dear Justin, Will you take us out after the show? Check yes or no.’ He checked yes six times. “

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Unfortunately, the night didn't exactly go as planned.

"We did some dancing during the concert. He was keeping it cool. He came down to us. That note just ignited something," the Pitch Perfect star recalled. "His manager was giving me the thumbs up, personally! Scooter [Braun]!"

She continued, "I still had Kelly to compete with. I didn't know which one of us he was going to choose if it went further. Or both. I was fine with whatever. And then he said, 'Uh, I just have to go and have a shower, and I'll meet up with you guys later.' So, we go back to Kelly's hotel room and wait. And then he never came."

Dakota chimed in again, asking, "What kind of excuse is a shower?"

To which Rebel replied, "Yeah, I know, because he didn't smell that bad."

Plus, the cast of How to Be Single share the three secrets to being single and reveal why their movie is the perfect girls' night out for Valentine's Day: