The short kiss goodbye
More than once I've initiated a stop and observed one occupant lean over to another for a quick kiss. Typically, it's the driver leaning first, but I've had passengers lean in first as well. This action should light up your "beware-o-meter", as obviously one of them knows they are going to jail, before you've even gotten out of your unit. The reason for their trip to jail are known only to them, until you've investigated and discovered it for yourself. Obviously, all vehicle stops are to be treated with great care and vigilance, but paying attention to even the smallest of clues can make the difference for us.