I notice from your profile that you live in San Francisco. Since you gave me such a great answer about insomnia I thought I'd go the extra mile for you and research this a bit. From searching on the California DMV web site I found the following page which speaks to everything from lost pink slip (title) to lost registration, license plates, etc.
In order to obtain a new pink slip for you're car, you will need to file for a lost title in the state and county you reside in. There is more than likely a fee to get a new one and the price is different based on each state. I would advise calling the courthouse and they should be able to tell you the necessary steps to take. Good Luck!