Who knew "Death Cookies" weren't something you ate?
Funny. In skiing, death cookies (a.k.a. "marbles") are the hard balls of snow that form, primarily from grooming machine imperfections, on the slopes, particularly in the mornings when the snow is still hard. The same terms are applied to the balls of rubber, sand, and debris that gather on the outsides of turns on NASCAR tracks. In either case, you get out into the marbles and your headed for the woods/wall.