CHILD: Look! Look at my finger!
MOTHER: Don't stick your fingers in random holes in the computer. You know better than that.
CHILD: But, why shouldn't I do that?
MOTHER: Because you might get a shock or something.
CHILD: But why?
MOTHER: I've told you before. Because computers have electricity inside them.
CHILD: But why do computers have electricity in them?
MOTHER: Because computers run on electricity.
CHILD: But why do computers run on electricity?
MOTHER: Because computers need electricity to work.
MOTHER: Because they need the energy from electricity to do things, just like how we need energy from food to do things.
CHILD: But, why?
CHILD: Why because?
MOTHER: Because I said so!
CHILD: Just because? Just because you said so?
MOTHER: Well, no, not really because I said so.
CHILD: Then, why?
MOTHER: Because e=mc². Can you say that? E equals M C squared.
CHILD: Because e=mc²?
I suppose this means he's feeling a bit better now. Right?
Too bad I'm not yet.
Edited to add: Bonus questions from the last hour:
"Mommy, what are Democrats and Republicans?"
"Is Hillary Clinton a Democrat?"
"Why is John McCain a Republican?"
"What does personal responsibility mean?"
"What does community mean?"
"Mommy, what is a virus?"
"Are viruses mean?"
"What do you mean viruses don't have brains? What is a brain?"
"But, why is my brain inside my head?"
"Mommy, why does your blog have all those whys on it?"