Michael Douglas Shocks Fans by Calling Wife Catherine Zeta Jones His 'Sister' in Birthday Tribute: 'Am I Tripping?'

Michael Douglas left fans scratching their heads after calling his wife, Catherine Zeta-Jones, his “birthday sister.”

The Hollywood power couple, who both celebrate their birthdays on September 25 — 25 years apart — shared sweet messages to each other on social media Thursday, September 25 — but Douglas’ affectionate post had people doing a double take.

“To my birthday sister — what a joy celebrating another year with you!” Douglas captioned a golf course selfie of the pair.

He added, “Congratulations on your spectacular game at the Celebrity Ryder Cup. Happy Birthday to the love of my life @catherinezetajones ❤️.”

Fans quickly lit up the comments section.

“That’s his wife not his sister, what do he mean birthday sister?” one person asked, while another chimed in, “Did you just call your wife sister?? Or am I tripping??”

Other gushed over the couple's sweet pics, writing, "A very happy birthday to you both! ♥️."

"Happy Birthday! 🎉 So cool you two share the same birthday…" a user added.

Zeta-Jones, now 56, returned the love with her own birthday post for her husband, who just turned 81.

“Happy Birthday Michael! Sharing this special day with you is once in a lifetime! 😘,” she wrote.

Their daughter, Carys, 22, also joined in with a heartfelt tribute.

“September 25th 🤍Happy Birthday Mom and Dadda!!” she shared alongside a family photo of Douglas holding hands with both her and Zeta-Jones. “Your love of life, love, learning, art… there are no words to describe my gratitude and admiration.”

The Chicago star also made headlines earlier this month during her appearance on Late Night with Seth Meyers.

Promoting Season 2 of Wednesday, in which she stars as Morticia Addams, Zeta-Jones admitted she’s meeting a “new generation of fans.” She recalled a moment on the golf course when a young admirer approached her.

“I was practicing, and this really cute 12-year-old boy came up, asking for my autograph, and it was like really cute, and then I went, ‘Haha. When I'm 70, this cute little boy will be like 33,’” she joked.

Meyers teased, “Now can Michael tell when you're doing math in your head like that?”

She laughed, “Yeah, he usually thinks I'm wondering what club to pick, and I'm not. I'm going, at that time, I'm sure it'll be fine.”

She even reminded viewers that Douglas is “25 years older” than her, turning it into a playful nod to their marriage.

Meyers cracked back, “That's good. As long as you know not to give them your number when they're 12.”

But not everyone thought it was funny as TikTok lit up with criticism.

One person said, “That twelve y/o boy comment was frickin wild.”

Another asked, “So, am I giving her a break because I like her, or is this as creepy as it sounds?”

“It's creepy. Who has these thoughts when they have an interaction with a 12-year-old?” one wrote.

Another person said it was “not appropriate,” while someone else summed it up simply, stating, “Well, that was awkward.”