What the guy said above is probably the best way, but you could always do a THOROUGH search of your car and then have them pull you over. Be very polite and nice but refuse a search, make them bring in the dogs. Maybe even act nervous just to make him even more giddy about busting you guys. He'll think for sure he has you guys and feel like an idiot when absolutely nothing, not even a spare paper on the floor, turns up. That will teach him when it takes up over an hour of his time and he looks like a tool to the rest of his department.

By the sounds of it, do you live in a small town?