Sweat pants, until the March, 1980, morning after a snowstorm when there was ice on the sidewalk at the street corner. As I slowed down to let a car go by, I slipped, feel, and my momentum took me off the curb and into the gutter, where about 1/4 inch of ice covered three or four inches of snowmelt.
I entirely soaked up one entire leg of my sweat pants in 32.1 degree water and still had another mile to run before I got back to my apartment.
That was the last of the really cold weather that spring, but I had better clothing options the next time I ran in that kind of stuff.