I think I talked about this before. When I was a late teen, I and my other underage friends would have a formal christmas party every year. Every year the cops would show up to a house full of respectable young adults, and even though they were underage/drunk/high, they'd tell us to have a nice night, and maybe think about turning the volume down a smidge.
Best plan ever.
On the same topic, a friend of mine has also a best plan ever to avoid confrontational situations with the Man, specifically when when driving under an assorted variety of influences (here in Rio the police is always on the street running what we call "blitzes" - short for "blitzkrieg" [1] - where they will stop cars on the street to inspect the passengers and the vehicle).
You basically, you know, shove your finger up your nose, turn the lights on and pass by the police barrier as slowly as you can. With your finger up you nose, really giving it a wiggle there. This has to do, my friend's theory goes, with the fact that people who go about their businesses calmly digging for gold up their nose cannot possibly be involved in any stressful, possibly illegal activity at that time. It's just the epitome of relaxed detachment, and he never got stopped not even once, he says - I have been in his car three or four times already while passing by one of those blitzes and we never had to stop. I remember trying to help it doing some nose exploration myself, but apparently the strength of this method is not cumulative and I was told on the spot to drop it, 'cos I was "giving it away".
[1] - yeah it's a misappropriation of the original meaning but we brazilians are cute and sexy and we answer to smug semantical correctness with the cadenced swing of our tanned hips