She "narks" on her own party by calling the police, but then uses a staged arrest as a social feature.
Watch this breakdown for a closer look at the rivalry between Homer and his new step brother, Calvin: [S34E8] Step Brother from the Same Planet
By convincing Chief Wiggum to drive her off in the back of a police car, she creates the illusion that she is a rebel, preserving her new "cool" status while successfully shutting down the party. She "narks" on her own party by calling
