how to fuck with the police

If you're ever stopped (and don't have anything on you...duh), and the police ask if they can search your car, the obvious answer is no. You have your right to privacy, and you shouldn't give it up just to save yourself time and trouble. People are treated like drug smugglers if they refuse a search, and police will employ a string of tactics to try to get you to allow them to search your car.

Here is where you have fun. Be polite, but at the same time try to be slightly evasive. Basically, do not give them "probable cause" or whatever to call in drug dogs and search your car, but leave them suspicious. Even though they don't have any grounds, they will probably still search your car thinking you have something you shouldn't.

Now you have a searched car without any contraband or even any reason to search the car.
A nice little situation you can report to the police department for misconduct, or contact the ACLU or NORML if you're feeling up to it.

Not only will this cause the police unnecessary trouble, it will help show that refusing a search is legitimate.