I would have better luck sexing a ceramic egg.
I was just checking out the listing again and noticed they have sold 21 of them. We have a term here for those people here. I will be nice though and keep my pie hole shut.
http://cgi.ebay.com/MAGNETIC-EGG-SEXER-hatching-eggs-chicks-chickens-/280560511724?pt=UK_Pet_Supplies_Poultry&hash=item4152b5aaec
How can that possibly work?