I read about this on Boing Boing this morning. Back in 1951, a sound designer for the film Distant Drums brought in a contract actor to record some screams to be dubbed into a scene in the movie. The scream then entered into the Warner Bros. sound library and has been used dozens of times since. it’s been dubbed “the Wilhelm scream” after the character who screamed it memorably in The Charge at Feather River. Check out this awesome compilation of Wilhelm screams on YouTube. And let me just say it now: Them! was a fabulous movie!