Little Sister: Mama, after you are dead, I going to marry Daddy!
Little Sister: Yeah...after you are dead.
Me: Well, I'm not planning to die anytime soon. And besides, you can't marry someone in your family.
Little Sister: Right. So I can't marry you or Annie or Daddy.
Me: (Not wanting to address the gender issues) Right.
Big Sister: (finally weighing in) You can only marry someone who is in someone else's family. And besides, Daddy is already married to Mama. You can't marry someone who is already married. Right mom?
Me: Right. You can only marry someone who is single. Someone who is not married is called "single".
Pause for about one minute.
Little Sister: I think Santa Claus is single.