Today watching a basketball game between teams of fifth and sixth grade girls in suburban Arizona, I heard one girl at the bench congratulating a teammate in this way: "Dude, that was perfect! You stole the ball!"
I laughed. I had heard high school girls/women in the kitchen where I worked use the word "dude," but had not thought about the word slipping down in age to little girls. It was like seeing a little girl slipping on big work boots and shuffling around.
My niece, B, said she did not like to use the word because "its weird." But her classmates do use it with each other.
Although dude has been used for males, it can be more easily widened to include females than the other common appellation, "man."