Quite graphic, if possible, ie I want something that doesn't skirt around issues like the digestive system including poo and farts and burps, and about willies etc (not necessarily sex although I'm not bothered if that's included as we'll have to talk about it at some point anyway).
Would also be helpful if it had something about germs and why it's not a great idea to stick hands down pants and then continue eating lunch 
Any ideas??