A common insult in American Spanish-speaking countries. It means "your mother's shell (****)", and it’s used as an expression of disgust for the person it is directed towards, by way of blaming his mother of bringing him into the world. It is extremely offensive when used between strangers. It originates from the phrase "de la concha de tu madre" (from your mother's ****) which comes from Chile. It may also be spelled conche tu madre.