The sole purpose of which is to let a person, most often a child, know when they are REALLY in trouble. When you are called this, you better be prepared for all hell to break loose.
John William Smith, you get your butt down here this instant!
Lily Ann Williams, what do you think you are doing young lady?
Person A: I gotta go, my Mum just used my full name
Person B: Ouch, hope you aren't grounded for long.