Take his current role as wild and weird Ethan Tremblay opposite Robert Downey Jr. as hardworking architect Peter Highman in Due Date, for instance. Zach explains:
"After the success of 'The Hangover,' Todd Phillips asked me to be in this new movie because I have a lot of confidence in Todd but not a lot in myself," Galifianakis says. "It’s new to me, especially if you have a big part such as this."
In the funny formula road movie, the ever-focused Downey plays an expectant first-time dad rushing to L.A. with Zach's clueless and aspiring actor in tow. Ah, but we digress.
"Anyway," the affable Mr. G continues, "Todd said, 'I’m thinking of Robert Downey, and Robert is an intense guy, and a very smart guy.'
"Maybe that was Todd's way of telling me to keep my mouth shut, but next thing I know, there was a lot of on-set discussions about every scene. Todd and Robert are alpha males. I’m certainly not, so I’d sit back and watch it -- and love it."
Zach guessstimates that the director and star "chatted" each morning of shooting for at least 90 minutes, including heavy arguments and shouting matches. Otherwise, Downey and Phillips got along famously, and the two continue to sing each other's praises on the eve of the film's Friday opening.
"The shouting is just (part of) their process," Zach says adding, "but why in my trailer? That’s my fucking question. You don’t say anything, you just sit there. Figure it out on the set, I don’t know what to tell you.
"I would read the minutes from the last meeting. 'Todd yells. Robert yells back. Let’s get on with the new meeting.'
"I'll tell you, though, it really helped it. It really did."
For more from Zach, Downey and Phillips, check out Sun News and CriticsChoiceMovies. You'll find my review of Due Date at both sites, too,
as well as my feature about "Megamind."