a phrase made popular by Paris Hilton and Nicole Richie on "The Simple Life" the actuall meaning of the word is still unknown, but its fun to sing in an annoying voice while dancing sideways across a street.
paris & nicole: "SONASA!!"
woman on bus: "can you please shut up?"
nicole: "wanna join our band? im billy, shes silly, and you can be willy"
woman: "whats the name of the band?"
nicole: "the sonasas"