It is essentially the countious process of MULTIPLE male participants ejeculating or so-called "cumming" into the same female (most commonly the vagina, mouth, or anus). The name comes from the reference to a shack as an often dirty dwelling which can be virtually used by almost anyone (hence the implication of a whore).
Sally is such a hoe! I bet she wouldn't mind becoming the school cum shack!!
by Maxxx 90703562 April 19, 2008