A tailgating teenager on a cell phone fails to notice that you've hit the brakes — until he's hit your bumper.

WHAT SHOULD HAPPEN: Both drivers get out of their cars in a safe area and exchange vital details, including driver's license numbers, vehicle makes and models, owners' names, and insurance companies and policy numbers. Your insurance company will need this information to approach the striking vehicle's company, and it will also help your insurer assess the damage. If you live in an area where police respond to minor traffic incidents (in big cities, they often don't), call them. Whether or not you involve the police, call your insurance company and report the accident as soon as possible. And remember, says Roger Albizu, the director of claim training and education at the insurance giant Geico, a photograph can be worth a thousand-word report: If you have a digital camera on your cell phone, use it to document any damage. This may be useful evidence later on.
IF YOU'RE GETTING THE RUNAROUND: Do not accept an offer of cash to forget the whole incident. You may later discover that your car or its passengers suffered more damage than initially thought. If the offender drives off or refuses to give his information, try to get his license number and call the police right away.