To protest against something that has happened. A: "How could you go through my things without asking?" B: "Oh, don't cry foul—I was just looking for my sweater and I found it. It's not a big deal." Dad cried foul when I forgot to put gas in his car after borrowing it.
cry foulprotest strongly about a real or imagined wrong or injustice.
Foul in this context means foul play , a violation of the rules of a game to which attention is drawn by shouting ‘foul!’
1998 Times She can't cry foul when subjected to fair and standard competition.
ˌcry ˈfoul(informal) complain that somebody else has done something wrong or unfair: When the Labour party candidate didn’t win the election, he cried foul and demanded a recount.
In sport, a foul is an action that is against the rules of the game.