EXCLUSIVE: 'Daddy's Home 2' Star Mel Gibson Gushes Over Welcoming Baby No. 9: 'It's Fantastic'

Daddy's Home -- and so is Mel Gibson!

The 61-year-old actor joins the second installment of the hit comedy starring Mark Wahlberg and Will Ferrell, and ET's Kevin Frazier got a first look at Gibson in action during a visit to the Boston set last
month.

WATCH: Mel Gibson Earns First Oscar Nomination in 21 Years While Holding His Newborn Son

"It's pretty dang cool," Wahlberg gushed of having Gibson play his dad -- despite the only 16 year age difference between them.

"It was difficult getting him to play my dad, because he's actually two years younger than me," he joked.

"Tell him you've been astounded," Gibson pleaded.

Wahlberg and Ferrell reprise their roles as father and stepfather in Daddy's Home 2, though this time around, they've joined forces to give their kids the perfect Christmas. The pair's partnership, however, is put to the test when their own fathers arrive just in time for the holiday.

John Lithgow joins the film as Ferrell's ultra-affectionate and emotional father, and while he jokingly called Gibson -- who plays Wahlberg's macho dad by contrast -- an "insufferable diva," it seems he's quite strict himself.

WATCH: Will Ferrell and Mark Wahlberg Reveal What Earned Them the Most Points With Their Kids!

"It's impossible. The man is an insufferable diva. He has no sense of humor. They talk about dead pan comedian, he's like a dead comedian," Lithgow said of Gibson, before ripping into Ferrell.

"There are strict rules about his schedule, and he has to go to school once every two hours," Lithgow teased.

"I just started solid foods," Ferrell laughed.

"He's still breast feeding," Lithgow cracked. 

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Of all the men on set, however, it's Gibson who arguably knows the most about little ones. The actor is dad to nine children, including 3-month-old son, Lars, whom he welcomed with girlfriend Rosalind Ross in January. 

"It's fantastic. It's always such a joy the little ones, you know? It's like being young again, seeing everything through their eyes," Gibson gushed.

"It's great because the first conversation that we had, we started talking about what I was going through with my 13-year-old daughter," Wahlberg added. "He was very helpful of giving me advice on how to deal with a teenager."

"Yeah, right! I've had a bunch of them," Gibson said.

Daddy's Home 2 hits theaters on Nov. 10, 2017.

WATCH: Mark Wahlberg Jokes About Daughter's Crush on Justin Bieber: They'll Date 'Over My Dead Body'

ET was also on the set of the first film in 2015. See more in the video below.