Like when you are riding along on your coaster equipped 1951 CCM (with a newer coaster hub) and a car comes out of a blind alley and cuts you off.

With a front brake I would not have broadsided the car but I did leave an impressive skid mark, managed to get sideways to the car to avoid a head on / OTB and only trashed my fork.

On a long enough descent a coaster brake will get hot enough to cook a small meal and the fade will reduce the power to almost nothing.