This is thanks to a review by Bookwyrm; it doesn't fully comply with his/her suggestions, but I hope you will enjoy it nonetheless. Again, sorry for inconsistencies.
There was a crash in the barracks, followed by the metallic cacophony of objects being scattered across the table, and concluding with the sound of rapid-fire cursing in French.
Down in the tunnels, by the radio station, Hogan sighed, and Newkirk muttered, "What's got up 'is nose now?" in reference to Lebeau (since it was unlikely that anybody else in the stalag would be yelling in French).
Carter said, eyes fixed on a piece of paper that he was playing with, "He can't find his spatula, so the pudding's gonna burn if he doesn't get it soon. He thinks you took it, Newkirk, and if you did, he wants to find it and stuff it down your throat."
There was a moment of silence before he finally looked up, and realized everyone was staring at him.
"...What? It's what he just said."
"Since when can you understand French?" Kinch finally asked, eyes narrowed slightly.
The paper was folded and twisted a few times.
"You mean you guys can't?"
"...No, Carter." Hogan leaned forward. "Has Lebeau been giving you lessons?"
Carter giggled slightly. "Not exactly. He talks in his sleep. Besides, I've been around him for almost three years now; that's given me enough time to pick up most of what he's saying. I mean, it's mostly a lot of angry stuff, including some things," his ears turned a little red, "that Mom wouldn't want me to say, but I can also tell a girl that I think she's really pretty, or instruct someone how to make creme brulee, and stuff like that."
The other three men glanced at each other in a way that demanded, How can he do that?! We've been here the same length of time, and still barely understand that 'bonjour' means hello, and 'boche' means German!
Carter prattled on, oblivious, "It probably wouldn't be that hard to learn more, because it's based on a romance language, so it comes from Latin."
"Wait, hold up," Newkirk interrupted. "Are you tryin' to tell us that you can also speak Latin?"
An enthusiastic nod. "I took some classes back home, before I joined up. It's handy for knowing a lot of science stuff. I would have taken Greek too, because that's also useful, but that's kind of harder because it's not even the same alphabet as ours. But as long as I have my Latin dictionary, it makes it easier for me to learn lots of other languages, even though sometimes I forget what language I'm speaking and switch off."
"...Any other languages you know?" Hogan asked.
"'E also speaks Lakotaese," Newkirk cut in.
Carter snickered. "That's not what it's really called, but yeah. I speak Lakhota. And I know a few insults in Swahili."
A scoff from the Englander.
He shrugged a little. "Hey, you never know when they might be useful."
Another burst of French came from upstairs; it sounded less angry than the earlier one. Even though it was slightly muffled, Carter still looked up in excitement.
"Oh good; he found the spatula. So the pudding's safe."
And with that, he finished folding the paper, revealing that it had been turned into an elegant origami butterfly.
Carter gently pressed his thumb on the top of it a few times, making its wings flap, before standing up, making it fly its way over and setting it on Kinch's head.
"I think he likes you," he said, before heading to the ladder and tripping on the lowest rung, almost breaking it under his foot before he regained his balance and scurried upstairs.
Kinch gently removed the paper butterfly from his head, and gave it an amused smile.
"No wonder he learned German so fast."
Newkirk shook his head slowly.
"Next thing you know, we'll find out 'e's learned the secret language of animals or something."
"He does have a pretty close relationship with that mouse of his," Hogan mused in semi-seriousness.
Newkirk threw up his hands in exasperation.
"Bloody -ll."