The best part is how Tom Hanks reacted.

"Future Man," which forced him to get naked. That experience "humbled" him so much, he finally felt ready to share the story of "the most embarrassing moment of my entire life."

The "Hunger Games" alum said he never told the story in public before, but the subject came up during his talk on "The Late Late Show With James Corden." Corden said, this time of year, "The Polar Express" is often playing on TV. Hutcherson, now 25, talked about his experience making the 2004 family film, which included some ill-timed on-set flatulence:

"It was crazy. That was my first big movie. I was like 9-years-old, and I was working with Robert Zemeckis and Tom Hanks. It was motion capture so we had these dots on our face and these weird wetsuit things. It's very, very odd experience. It was cool."

Until it wasn't.

"I was shooting this scene with Tom Hanks, who's like the father of the world. And we're shooting this scene where he's playing the hobo and he's on top of the train skiing down and I'm nestled under him like, 'Whoa this is crazy.' And I farted. I farted in the scene. It happened. I did it. And instead of playing it cool, Tom Hanks was like, 'Whoa whoa, Oh my God, this kid! What the heck? Oh my God!' My first big movie? Tom Hanks, Robert Zemeckis? And I just farted in his face -- in his crotch!"

(Well, that gives new meaning to the toot toot of the train engine...)

Looking back, it's funny, Hutcherson said, but in that moment he thought his face would sweat blood. James Corden said that level of shame allowed him to put on the prosthetic penis for "Future Man." So it was a good learning experience all around.

Watch Hutcherson tell the story:Watch "Future Man" on Hulu. And if you do watch "The Polar Express" this holiday season, try not to let this fart story completely dominate your thoughts.

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