The Animal Game

A favorite game to play while driving in the car is the Animal Game. We take turns thinking of an animal and everyone else asks yes or no questions until we guess the right animal. Daniel has just recently started taking a turn, although we aren't quite sure if he is really grasping the game yet. We'll ask a lot questions and he'll reply with yes or no, until we finally guess an animal and he says, "Yeah, that's it." But we're suspicious of the fact that he might not really be thinking of an animal from the beginning. So yesterday on the way home from church we were playing this game, and it was Daniel's turn. Here's how it went:
"Can this animal fly?"
"No."
"Does this animal swim?"
"No."
"Does this animal walk on four legs?"
"No."
"Does this animal have legs?"
"No."
"Is it a snake?"
"No."
"Is it a snail?"
"No."
"Is it a worm?"
"No." (At this point I thought we were going to have him trapped, he wasn't really thinking of an animal, just saying yes or no.)
"We need a clue."
"It starts wif a 'B'."
"Hmmm.... we give up. What is it?"
In a monotone voice, "A bis----."
"A bicycle?"
Again in a low, monotone voice, "A bison."
"Oh, a bison! Of course!"