Best Place To Keep Money

Akpos was always stealing his mother's money any where she hid it. The mother, very confused about what to do, decided to talk to her husband about it:

WIFE: I don't know where to hide my money from Akpos. He has discovered all the secret places I keep my money.

HUSBAND: It's very simple. I know where you can hide the money from him. He won't know where it is.

WIFE: (excited) Where?

HUSBAND: In between his school books!