What is the dumbest thing you have seen while on the road?

Here is southern CA it is usually a move related to impatience. Cutting off traffic or lane change to get a 5 second advantage. A marginal pass to get another 2 MPH for a few minutes. The risk/reward scale is out of whack.

This month's honors: The guy on hwy 395 north of Adelanto, maybe in Red Mountain, who passed a line of vehicles through multiple left turn pockets and median marked no passing.