The answer is to grow up to be a >gasp!< conservative... that'll piss them off. But not just a arrogant, pompous, spinmeister of a conservative; that's been done. Besides, your parents sold out their ideals in the '80s anyways, and they'd secretly like you to get rich so they don't have to help you pay off your student loans. Here... try this.
To start with, change your religion. Try Islam. This will only temporarily confuse your parents, who used to be Cat Stevens fans. Quick, push the limits before they start to accept you. If you are a female, you could ask your parents for a loan so you can afford to get your clitoris surgically removed. If you are a male, however, you could change your name to Abdul Hamid, run off to Afghanistan, and fight for the Taliban. Won't your parents be surprised when you finally make it on to CNN?!
This has "Made for TV movie" written all over it...