yadida started as a alternate way to say "you know" in the bay area.. gradually over the years slang changes. it is most commonly used now as a slang word for cocaine

Another ebonics created by the black people of the Yay Area. Shortly after the king of the bay (Mac Dre) died, the word became famous from the song "Super hyphy" by Keak Da Sneak, but the words origin came from Mac Dre.