Deep voices run in the family of actor Will Arnett, who is a hilariously narcissistic version of the caped crusader in The Lego Batman Movie.
So he did not have to change his baritone much to affect Batman's trademark growl.
"My dad has a pretty deep voice too - not as badly as I do, or as well, depending on how you look at it. And kaching, obviously it's 'well'.
"By the way, my dad has always claimed that if anything happens to me, he could take over my career. Thanks a lot, dad," says the 46-yearold, who was nominated for an Emmy for his role in the sitcom 30 Rock (2006-2013) and appeared in the Teenage Mutant Ninja Turtles movies (2014, 2016).
At a press event in Los Angeles earlier this week for the movie, he is joined by Zach Galifianakis, who voices Batman's emotionally needy nemesis, Joker.
Galifianakis says, deadpan: "I have a follow-up question - did your parents feed you tarmac as a kid?"
Arnett replies: "Well, just for the vitamins and stuff, we always had a steaming cup of crushed glass in the morning."
Get Arnett and Galifianakis in the same room and you can sit back, break out the popcorn and watch two hair-trigger wits spark off each other, producing an unending stream of silliness with the occasional nugget of comedy gold.
Any hope of a straight-faced interview vanishes as the pair turn each answer into a comical digression, covering subjects as varied as the continent of Australia ("it's all the crooks and rejects from England", Arnett declares) to plastic surgery for their children, which they both claim to be in favour of.
Their chemistry came in handy when director Chris McKay (Robot Chicken, 2005-2011) put the duo in a recording booth and asked them to flesh out the themes in Batman and Joker's love-hate relationship.
They ended up playing it as codependent and faintly homoerotic, which gets some of the biggest laughs in the film.
"A lot of it was improvised," says Arnett. "Zach and I had a day when we were in a room and Chris miked us up. We kind of knew the area we were going to play in and just started digging out that relationship. And turned it into, basically, a rom-com between two enemies."
Galifianakis, 47, best known for The Hangover films (2009, 2011 and 2013), thinks their being in the same room, rather than recording their voices separately, which is how many of such films are now made, was crucial.
"You want Will there to riff off of because it's helpful. Chris, the director, obviously knows what he's doing and can get from the actors what he needs. But being in the room was the old-fashioned way of doing it. We found the themes of our relationship that day."
Arnett adds: "And it really drove the narrative throughout the film."
The animated feature - which shows Gotham's hero being plunged into an existential crisis when Joker unexpectedly surrenders to the police - pokes fun at earlier adaptations of these DC Comics characters.
But the stars also drew inspiration from some of the earlier films, both citing director Tim Burton's Batman (1989) - which had Michael Keaton in the title role and Jack Nicholson as the Joker - as the definitive take on the characters.
"Jack Nicholson's Joker was perfect," says Galifianakis. "That's the one that made an impression on me.
"That live-action version of Batman is the most cartoony, but also the creepiest, in a great way. What they did with Jack Nicholson's make-up, putting skin make-up over it, is very eerie.
"And there were so many non sequiturs that were just so wonderful."
Arnett points out that Keaton's deep and raspy Batman voice now defines the character. "His Bruce Wayne to Batman transformation was very different - they were different characters. His growl was as deep and dark, perhaps, as Christian Bale's (in The Dark Knight films, 2005, 2008 and 2012), which was great too.
"And it was very fresh. He and Tim Burton came up with the idea that Batman talks like this. That's what we have come to take for granted now. And at the same time, when he was Bruce, he was kind of playful - a playboy and bon vivant. Michael Keaton's an amazing actor and I think he doesn't get enough credit, just because there have been so many other good Batmans."
What do the actors' children think when they hear their voices emanating from animated Lego figures?
"They say, 'Can I have my iPad?'" quips Arnett, who has two sons, aged six and eight, with ex-wife and Parks And Recreation star Amy Poehler, 45.
Galifianakis - who is married to charity founder Quinn Lundberg, 33, and has two boys aged three months and three years - says: "I usually get, 'You're not my real dad.'
"I have this television show on (Baskets), and my picture was on the side of a bus and my (older) kid saw it. I looked in the rear-view mirror to see what his reaction was and he looked at it, knew it was me, but just looked straight ahead and sighed."
Arnett reveals that his kids were a little more enthusiastic about his work this time because they were roped in as voice actors on the film.
"They are the voices of two orphans who go 'Batman, we love you, we love you!'" he says.
"Well, you know, there's no nepotism in Hollywood," Galifianakis remarks wryly.
•The Lego Batman Movie is in cinemas in Singapore.