The Stain females get when excreting wastes into an undergarment either on accident due to a joke being told, or while in their sleep. This can also be an insult to guys who accidentally pee on themselves while using the bathroom
Derek: Dam Craig is That a C stain on your pants man??!!?!
Craig: Yeh sorry man, i accidentally went on myself when the guy next to me slipped and knocked me over while iwas going.