I've got one of these too. When I was 6 or 7 I read a book in the school library in which the villains were the "bone people" and the heroes were some sort of space explorers. The bone people could read minds, so they could tell everything the heroes were planning and thwart them.

Eventually the heroes learn to keep their true thoughts in the back of their minds, where the bone people can't access them, and with this technique they eventually defeat the bone people. It was the best book I'd ever read (up till then!) and I remember practicing keeping my thoughts in the back of my mind.

I've been trying for years to find this book again. Anybody have ideas?