Passing on the right. . . Missouri style!

On my way downtown to get a greasy burger I was traversing da 'hood on I-70. At the Jackson curve some guy was drifting into my lane, so I slowed down.  He hung in there until the freeway curved left. He was crossing the solid yellow line, so I put the brakes on. A car was passing us on the right just as he kissed the left rail and hurtled across all three lanes. She hit the brakes just in time. I rolled my window down and she did too. She just said, "Holy fuckin' shit!" So, I pulled up beside the guy who hit the rail, who was now driving very slowly in the far right lane, and I honked, pointed at him, and made an OK sign. He nodded and waved me on. I don't know what drugs he was on, but he didn't need to be driving.