Starting at 6:30 p.m. and extending throughout the evening the SFPD will be doing a sobriety checkpoint at an undisclosed location to look out for drivers who partook too much of the Jameson's and green beer. We're guessing SoMa, near a bridge approach, but the strategy has also got to include an area where cars can easily bolt in another direction when they see a sobriety checkpoint up ahead. Any other guesses?