Divination book title

[justcarol67]

Kemper wrote:
> There's a subtle difference.
> Arduous or monotonous work is ballbreaking.  
> To break someone's balls is to demand of them to perform a real or perceived ballbreaking task generally at a time of their inconvenience. (<---That's an ugly sentence, but I hope it's understood!) 
> Ball-breakers are taskmasters.

Carol responds:
Well, yes, but JKR is British and female. Though she does sometimes use double entendres, the implications here don't seem to fit with misfortune. I think she's going for the crystal ball image and the alliteration--though I must admit that as an American who hears adolescent boys talking quite frequently, the other reading did cross my mind.

Carol, who thinks we should trust the British readers on this one