Oil!

Bunny came back into the house, and followed Dad into his study and shut the door. "Dad, are you really going to put up that money with Mr. Roscoe?"

"Why, sure, son, I got to; why not? " Dad looked genuinely surprised -- as he always did in these cases. You could never be sure how much of it was acting, for he was sly as the devil, and not above using his arts on those he loved.