full Britney
Accidental (or perhaps intentional) opening of legs while wearing a skirt or dress without undergarments.
And when she stepped out of the car, it was obvious that she went full Britney tonight
the full Britney
Shaving off your long hair on a whim, like Britney Spears did.
My hair is starting to look like a mullet, so I think I'll give myself the full Britney.