Matt Damon Talks Daughter's 'Really Bad' Jellyfish Incident, What George Clooney Is Like As a Dad

The 'Suburbicon' actor recalls the scary moment as 'the worst thing.'

Matt Damon getaway to Australia wasn't exactly relaxing!

The 47-year-old actor was a guest on Thursday's episode of The Ellen DeGeneres Show, where he opened up about his family's April vacation with Australian actor Chris Hemsworth. Damon recounts the not-so-fun moment when his 7-year-old daughter, Stella, had a scary incident at Byron Bay.

"Australia's famous for having a lot of poisonous things, and I'm telling my kids, 'Don't worry. It's fine,'" he remembers. "And Chris is like, 'Oh, you'll be fine. Come on over.' And my daughter, my [youngest], got stung by a jellyfish."

"It was the worst thing," he adds. "I mean, even Chris said, he was like, 'Mate, that's the worst thing I've ever seen in my life.' Like, it was really bad. She was in a little bit of surf, in about a foot or two of water... this thing literally wrapped around her. I could show you pictures that would turn your head. She had these, it looked like red shoelaces around her body."

Damon continues on, telling host Ellen DeGeneres he and Hemsworth had to physically pull it off Gia.

"[I got stung] a little bit, but not like her," he explains, adding that neither of them peed on her, a method that is supposed to help ease the pain of a jellyfish sting. "That's what they say you're supposed to do, but -- at this point, you know, she peed on me enough in her life. But, no. In fact, there was enough around her chest that a lot of locals said, 'You should actually call the paramedics,' because you can go into shock."

"They showed up and said, 'Actually, hot water [helps],'" he adds. "Like if you put her in a hot bath and just gently sponge away [the stings]. They stick to you with these little needles, basically. It's really painful."

In addition to Stella, Damon and his wife, Paige, are also parents to daughters Isabella, 11, Alexia, 18, and Gia, 9, so the two definitely know a thing or two about the highs and lows of raising girls. Later in the show, DeGeneres asks Damon if he has any parenting advice for his Suburbicon co-star, George Clooney, who is a new dad to twins Alexander and Ella with wife Amal.

"It took him into his fifties but I think he grew up, finally," Damon jokes. "No, he's loving it. He's great. He's a lot calmer than I -- with twins, that's a lot of work. But he did confide in me that they went onto solid foods last week, so he's trying to get off diaper duty now. Because that's a whole other level."

"He was like, 'Diapers are easy!' and I was like, 'Wait for it,'" he adds. "The twins thing, people ask me if I give him and advice and I'm like, 'No. Two babies at once? That's horrific.'"

ET caught up with Clooney over the weekend, where he revealed his twins' latest milestone and his family's Halloween plans.

"We're still getting used to having human beings in our life," he shared. "Two little human beings that we are responsible for. But it's pretty funny and it's wild."

"This is an important part of my life's journey and this is really, truly the largest step in fatherhood for me at this point," he added. "Three days ago, my children started on what we would call solid food. I don't know how it goes in as a carrot and it comes out the way it comes out. But it was shocking. It was shocking what has changed. And I think it may never go back. I think it's going to be that way forever now, and it was terrifying."

Hear more in the video below!