"Daddy?"
"Yes, Jack?"
"Why does Santa like the cold?"
"Well, he's used to it."
"Because he's a jolly old elf."
"I would imagine that's part of it."
"And he lives at the North Pole, where it's always cold."
"That's true.  Who else likes the cold?"

"Polar bears."
"That's a good one.  Santa's like a polar bear."
"Santa's not a polar bear; he's an elf."
"You're right.  But he's like a polar in the way that they like the cold."
"And they both live at the north pole.  They have that in common."
"That's right."

"Daddy?"
"Yes, Jack."
"Weeee have a lot in common."
"We sure do.  Like what?"
"Uh...math and counting, we can both do that."
"That's true.  What else?"
"We both like decorating Christmas trees and playing in the snow."
"Yes we do."