" So . . . what is this fire river called?”
“The Phlegethon,” [Annabeth] said. “You should concentrate on going down.”
“The Phlegethon?” [Percy] shinnied along the ledge. They’d made it roughly a third of the way down the cliff—still high enough up to die if they fell. “Sounds like a marathon for hawking spitballs.”
“Please don’t make me laugh,” she said.
“Just trying to keep things light. "
― Rick Riordan , The House of Hades (The Heroes of Olympus, #4)