The arm, specifically the right arm, a mother (or other driver) uses to protect the person in the passenger seat when they slam on the brakes. This arm is quickly forced in front of the passenger to ensure they do not move the, roughly, three inches they would normally go forward during an abrupt stop.
Thank god she used the soccer mom arm or I would have flown into the windshield!
by vades May 23, 2007
Get the soccer mom arm mug.