Flaking is the term for what happens when a player drops out of a game without warning or reason. Sometimes there are legitimate reasons for doing this, such as extended illness or computer/Internet access problems, but sometimes a player just loses interest or leaves the site altogether. Either way, the problem usually results in the Game Moderator having to find a replacement, although sometimes they will modkill a player if no replacement can be found in a timely manner.
Flaking usually has a negative impact on a game, causing it to stagnate while a moderator searches for a replacement, often bringing discussion to a halt and, in the case of resulting modkills, upsetting a game's balance. It is considered rude and discourteous by most members of mafiascum because of the problems it causes. In addition, it breaks the self-contained nature of the game by bringing a previously-uninvolved player into the game, who may play very differently from the replaced player (for better or worse).