If a kid asks where rain comes from, I think a cute thing to tell him is "God is crying." And if he asks why God is crying, another cute thing to tell him is "Probably because of something you did."
The face of a child can say it all, especially the mouth part of the face.
"If you lived in the Dark Ages and you were a catapult operator, I bet the most common question people would ask is, 'Can't you make it shoot farther?' 'No, I'm sorry. That's as far as it shoots.' "
"You know what's probably a good thing to hang on your porch in the summertime, to keep mosquitos away from you and your guests? Just a big bag full of blood."
If you ever fall off the Sears Tower, just go real limp, because maybe you'll look like a dummy and people will try to catch you because, hey, free dummy.
....I could go on for days, but I won't.