This trope is the tendency, particularly in older films, to avoid harsher age ratings by displaying blood in an unrealistic, thick, bright red. Will give the impression that mortally wounded characters have just had a tin of red paint poured over them. Prime examples : almost any 70's action films, e.g. the Dirty Harry or Death Wish series.
Hello, Unknown Troper. You'll need to get known to lend a hand here.
Three days must pass before this YKTTW is Launchworthy or Discardable