Throw Your Tooth on the Roof: Tooth Traditions from Around the World - Selby B. Beeler, G. Brian Karas
I really thought the title was a one-off. Who knew so many people literally throw their teeth on the roof! Ha! We actually got super nerdy with this and made a bar graph to chart the frequency of various traditions. Move over tooth fairy, the rat and the roof take the prize! Lots of fun!