Even Pink has to work to earn her cool mom points!

The 36-year-old singer joked to ET that she's "in trouble" with daughter Willow, who will celebrate her fifth birthday in June, after revealing her little girl's crush on The Martian star, Matt Damon.

"She's already upset with me because there's a new game we play called Ask Siri -- which, she just found out last week there's a Siri -- and I said, 'Siri, Willow-Matt Damon' and all this stuff came up," Pink said on Tuesday, sitting down to discuss her new single, "Just Like Fire," which is featured in Disney's Alice Through the Looking Glass.

WATCH: Pink Jokes About Combative Marriage With Carey Hart, Says They're 'Due' for a Break 

"[Willow]'s like, 'How do they know?' She got mad at me!" Pink continued. "I was like, 'Oh my God, I need to keep my mouth shut. Sorry!'"

In an interview on the Kyle and Jackie O radio show on KIIS 1065 last week, Pink let it slip that Willow's favorite movie is The Martian, for a very specific reason. 

"It's good. She loves it. I love it. I thought it was great, but I don't love it the way she loves it," Pink revealed. "She asked me if Matt Damon can come to [her birthday party]. I think she has a crush."

But as it turns out, Willow's crush is pretty serious.

"She wakes up and rolls over and goes, 'Matt Damon,'" Pink admitted to ET with a laugh. "I'm like, 'I know.' ... I'm thinking I'll get her a Matt Damon poster [for her birthday]. I've never talked about Matt Damon this much in my life! She made me google Matt Damon dolls. That was disturbing. Do that sometime, they're very disturbing."

The adorable, "boy crazy" tot got a taste of mom's work life on the set of her "Just Like Fire" music video recently, where she developed another surprising crush: Johnny Depp's stunt double!

"He's a very charming man," Pink gushed. "She loved him. She also wakes up, if it's not 'Matt Damon,' it's 'Mad Hatter.'"

WATCH: Pink Says Willow Is 'Mean' Like Her, 'Cute' Like Her Dad 

Pink also opened up about her "tough" parenting style and how Willow has to earn her way to the Alice Through the Looking Glass premiere.

"She has to feed the dog, she has to make her bed," she added with a laugh, "She has to be nice to me, let me sing in the car, because she won't let me sing in the car."

The three-time GRAMMY winner said that Willow calls her singing voice "distracting" and has even harshly declared, "'I love you, mom, but you're very disappointing.'"

"She's a fireball," the singer said, admitting that Willow is already following in her musical footsteps.

"She's pitch-perfect and she's loud, which is always good... If you can't hit the note, just be loud," Pink said. "I just let her be free and wild. I just love watching the world through her eyes. She's completely unjaded, unstained. She's just amazing."

As for her own musical offerings, Pink admitted that she's "been writing" songs but has no solid plans to release them yet. "I'm winging it right now."

WATCH: Pink Regrets Calling Prince a 'Rude F**k' When She Was Younger 

Pink (real name: Alecia Moore) also got candid about losing Prince, who died on April 21, and what she would say to him today if she had the chance.

"He was a musical genius," she said. "I did get to see him perform at Coachella many, many years ago, and it was a magical moment to me. And to someone like that, I would just say, 'Thank you.' That's all you can say."

Alice Through the Looking Glass hits theaters on May 27. Go behind the scenes with Anne Hathaway, Mia Wasikowska and Helena Bonham Carter in the player below.

WATCH: Behind the Scenes With the Cast of 'Alice Through the Looking Glass'