If you are dressed and stopped by the police, for any reason, DO NOT PANIC. Simply answer their questions, do not elaborate. You don't need to tell them you are dressed because you lost a bet - they don't care. Be honest but not overly forthcoming - they don't care. Duana mentioned she has been pulled over in Mexico. She had a good experience, but I think she was lucky as Mexico is a male dominated society and she may have found the one police officer with some amount of sophistication; most will look unfavorably upon you unless you are in a VERY urban setting.
The police are only interested in you because they suspect you committed a traffic violation, so the best thing to do is not run or cruise a stop sign, signal all of your turns, don't speed (or drive too slow) and make sure your car has all of its equipment working. Make sure you have your license, registration and proof of insurance with you.
If you get stopped because you have been drinking, then you'll get what you deserve, and spending the night in a drunk tank dressed is not an experience you'll soon forget.