I had a car drifting left toward me on the interstate on my 'wing, and when I honked the horn it startled her so badly she over corrected and ran off on the shoulder to her right. That apparently startled her so badly that she over corrected again and made another run at me, whereupon I honked again and she hit the shoulder again. This time she settled back into the right lane, and I cautiously rode up beside her and looked. She was banging on the steering wheel with both hands and yelling. Jeez!