Toph
Zuko hasn't gotten much better at cracking jokes, but that doesn't mean he's stopped trying. Side effect of existing in Sokka's general vicinity, probably. That's fine with Toph, because though the jokes are bad, the trying is funny.
Of course, even a blind man is bound to find a door after walking into enough walls. Not that it's ever been a problem for her.
Aang's regaling them with another story about his adventures with Kuzon in the Fire Nation as it was a hundred years ago. He's been doing that a lot lately, probably, Toph thinks, trying to make Zuko feel more comfortable (from the firebender's reactions, usually only half succeeding, while Katara gets more and more irritated).
"And then we heard someone coming so we ducked behind the doors, since nobody but the Fire Sages were supposed to be there, and you'll never guess who it was!" Aang is rambling on animatedly, bouncing in place.
"…The man with the black helmet?" Zuko suggests half under his breath, and for once his timing is perfect and it's hilarious.
"The what now?" Sokka asks quizzically, while Aang huh's in confusion and Toph snorts, then starts giggling.
"The—never mind," Zuko is quick to back down, shifting uncomfortably in his seat on the stone floor.
"…And why is Toph laughing?"
For some reason, the fact that nobody else seems to get the reference just makes it even funnier. "He must have seen a crooked feather on a sparrowkeet and realized where they were," Toph manages, not able to make it quite deadpan, and she can feel Zuko shaking with silent laughter.
"A hook-shaped dust cloud," he says, and they're both done for, nearly falling over each other laughing.
"…Either you two have gotten a hold of some cactus juice, or I'm missing something here," Sokka said, brows quirking.
"It's—this ancient epic," Zuko says, stifling his laughter. "The Epic of Ran Meng."
"…Eh?"
"It's this really awful old poem," the former prince tries to explain, "about this sage named Ran Meng, and this giant white toad—"
"It's the longest, most boring story you can imagine," Toph interjects. "It's really the same story over, and over, and over, and over again. The guy had no imagination."
"No kidding," Zuko agrees fervently. "We had to read it at the Boys' Academy and we all hated it. But—"
"I couldn't read so I had it read to me," Toph says, crossing her arms and turning her face in his general direction. "It took six months."
"…Ugh. That's horrible," Zuko concedes to her oneupsmanship. "Anyway, the black helmet guy just keeps popping up wherever Ran Meng goes, but it's always—"
"Hm. Someone who shows up unwelcome wherever you go. Sounds strangely familiar," Katara says, and that just kills the whole mood, which was actually relaxing a little.
Toph's getting sick of that. So she stage-whispers, "He was probably able to find you because you guys kept leaving grains of sand out of place!"
Given how tense Katara is, Toph figures she's probably glaring at Zuko, but even that can't keep him from having to smother a huff of laughter with one hand.
"I still have no idea what's going on," Sokka says forlornly.
"Me neither," says Aang.
"Count yourself lucky," Toph chokes out through her giggling. "You were spared the joys of an aristocratic education."