Woah, are you serious? So could they do something like 'Yes sir, I know you have Miranda rights, but since they passed <bs law> on <bs date>, if you are caught with possession of <some drug>, you no longer have the right to remain silent, and if you do, it can add up to <ridiculous amount> dollars to your charges.'
What if the guy confesses something there and then later finds out the cop was lying? Can he do something about it?