A didjeridu is a sort of trumpet that is used by the aborigines of northern Australia. Made from a eucalyptus tree branch that has been hollowed out by termites (yikes!), one end is carved into a mouthpiece. Blowing into it while making a humming sound in your throat -- like when you play a kazoo -- produces a droning, buzzing sound. The instrument is used to accompany singing and dancing, and is sometimes decorated with cool designs.