Warner Bros.

Even Matt Damon Hasn't Heard BFF Ben Affleck's Batman Voice Yet

Some things you don't even reveal to your friends.

With reporting by Josh Horowitz

If you think you're excited to see Batman in "Batman V Superman: Dawn of Justice," just think of how Matt Damon, longtime best friend to dawning Batman Ben Affleck, must feel.

"I haven't heard the Batman voice yet!" Damon told MTV News while doing press for "The Martian" at Toronto International Film Festival this week. Secrets!

True, we have heard a snippet of how Affleck will treat the character in teasers and trailers... But that's been a heavily vocally modified version, filtered through the insane metallic suit Batman uses to fight Superman. So basically, we're in the same boat as Damon.

Even if he hasn't heard the Batman voice, though, Damon did hear Affleck's regular voice before the latter took the role. Because he called him. On the telephone.

"I talked to him about it. It was a big decision," Damon recalled. "He knew what the stakes were. Once he was able to get Chris Terrio to write the script, I think that made the decision for him. Chris is a fantastic writer and Ben really liked Zack [Snyder], who's directing, and it was like, 'well, I've got all the pieces that are necessary.' "

While he may not have gotten Affleck to give him a preview of the Bat-voice yet, it's impossible to miss the major bulk Affleck has put on.

"He put on like 30 pounds, which took him like nine months," Damon added. "He put on like 30 pounds of muscle, which is really not easy to do. You've gotta eat a lot. You've gotta be an omnivore. Or just greedy."