Discription of Events: Man was recklessley driving on 101 south just between Edgewater blvd and the foster city blvd. exit. He was swerving in between very dense traffic, not using his signal lights, and tailgating. I felt in extreme danger particularly when he cut in front of us, sped up and swerved across 4 lanes to pass us, then cut across lanes again just to tailgate my car and then pull up dangerously close to our left side to scream " do you have a problem" at us. He stopped traffic when he did this, creating an even bigger traffic issue. I exited as soon as I felt safe to do so, for fear he was going to follow/tailgate.