She got what she wanted: your attention, negative or positive (in our minds), it doesn't matter. So you rewarded her and her behavior increased.
The first sign of trouble? Time out without saying anything. But you have to be fair and get her mentally and physically tired first before you sit down.
Hey, you have GSD!!
Deja, GSD, sable WL, female, born 11 / 2013
Cam, Rough Collie, sable, male, born 8/2015