Star Playdates: Celeb Kids Who Are Friends

— -- Famous parents flock together, so it's no surprise that their offspring get along, too.

Take Hilary Duff and Jack Osbourne's wife, Lisa Osbourne, who have been friends for years.

Their babies -- Duff's son, Luca, who will be 3 next month, and Osbourne's daughter Pearl, who will be 3 in April -- have grown up together, attending the same baby class in Hollywood and, most recently, sharing an ice cream date.

"Two of the sweetest babes I know, Luca & Pearl! @hilaryduff #icecream #gelato," Osbourne, a lifestyle blogger, wrote on her Instagram account, sharing a picture of the two kids having a sweet treat Monday.

Duff posted a black-and-white snap from the outing on her own Instagram account.

"Luca&Pearl's ice cream date @mrslisao we made some cuties," the "Lizzie McGuire" star wrote.

Check out these other cuties on their celebrity playdates.

North West

The famous daughter of Kanye West and Kim Kardashian has regular playdates, and often they're with the children of other famous people.

Kardashian's friend, Ciara, has introduced her son to the toddler, and last year, the "Keeping Up with the Kardashians" star photographed her daughter playing with the daughter of pal Larsa Pippen. However, it seems North's most constant companions are her cousins, Kourtney Kardashian's two oldest children, Mason and Penelope.

Ace Johnson and Rocco Faison

Former "Scrubs" star Donald Faison and Cacee Cobb, his wife of nearly two years, welcomed Rocco in August 2013. Since then, the little boy has enjoyed plenty of playdates with Ace Knute Johnson, the son of Cobb's best friend, Jessica Simpson, born in June 2013.

"BFF's in the making! @caceecobb #ACEANDROCCO," Simpson wrote next to a sweet shot of the boys playing in February 2014.

Last July, she posted another snap of the boys on a playdate. They'll have to make room for Rocco's little sibling soon. Faison and Cobb announced in October that they are expecting their second child.

Jennifer Garner and Brooke Burke-Charvet's Kids

Both moms of large broods, Jennifer Garner and Brooke Burke-Charvet spend a lot of time together because their kids not only go to the same school but carpool together.

The former "Dancing With the Stars" co-host told Us magazine in 2013 that she would trust Garner, a mother of three with husband Ben Affleck, to babysit her own four children.

"[Jennifer] is very normal," Burke-Charvet told Us of the A-list actress. "And she and I carpool together -- so I trust her!"

Drew Barrymore and Jimmy Fallon's Girls

When Drew Barrymore stopped by "The Tonight Show" last November, she and host Jimmy Fallon gushed about their kids' friendship.

"Our babies play with each other," said Fallon, 40, showing pictures of his daughter, Winnie Rose, who will be 2 in July, playing with Barrymore's two girls, Olive, 2 1/2, and Frankie, who will be 1 in April. "They're pals!"

That's because Fallon and his wife, Nancy Juvonen, have been friends with Barrymore and her husband, Will Kopelman, for years. Barrymore and Juvonen run the production company Flower Films together, and the actress starred opposite Fallon in the 2005 romantic comedy "Fever Pitch."

Neil Patrick Harris and Elton John's Kids

Fathers Neil Patrick Harris and Elton John have gotten their broods together for family vacations, at least since 2010. Harris and his husband, David Burtka, are parents to twins, Gideon and Harper, who will be 5 in October. John and his husband, David Furnish, have two boys, Zachary, 4, and Elijah, 2.

The famous friends recently got their families together for a beginning-of-the-year trip to Hawaii.

A month later, John, who sang at Harris and Burtka's wedding last year, brought his boys by the Oscars so they could cheer on their Uncle Neil.

"The boys stop by for a visit in the sweetest little black tie dinner suits. They are so happy to see Uncle Neil on the big screen!!@Ejaf #Oscars," he wrote alongside a snap of him, Furnish and their sons.