I have been harassed by the police, had my civil liberties stomped on, been arrested, and had to pay a lofty sum in cash and time. And I also used to say "fuck the police!"
And I have now chosen to take my power back from them, by being far more threatening to their status by no longer giving them power over me by merely saying "fuck you." Instead I chose to confront them with intelligent, fact based, adult conversation which truely puts them in their place. You will get much further in chanting down Babylon if you step out of the playground and onto an official pulpit.
Use your brain instead of your anger, for anger is the only thing they know how to respond to. That is giving them your power, only to open yourself up to further repression.
Down with tyranny, up with intelligence!
Again, if my presence, knowledge of police attitude that night, or any other help I can provide is desired, please do not hesitate to call on me!