Specifically the negative or immature demeanor, associated behaviors, silver-spoon fed, pompously
inappropriate, childish, and rude mannerisms most commonly expressed by a rotten
little sister who has somehow envisioned herself to be worthy of a position of power and sharp tongue, which she clearly has not earned. To act in a rude, disorderly, or otherwise unkind fashion towards an older brother or sister without cause,
justification, or reason.
An older brother called his youngest sister whilst she was away at her freshman year of college
just to say hello and see how things were going, however he could not spare the time of day to say hello and
shoot the breeze, so instead of being friendly, the
little sister copped a fierce brattitude, saying something with a dismissive and judgmental tone about how she had to go because it was time to eat dinner. Huh, I guess older brothers aren't worth a dime's worth of respect and friendliness for some unexplained reason.