What with me being a sound guy, I'm a fan of obscure film trivia related to sounds. The "Wilhelm Scream" is a great example of this.
In the early 50s, a character in a western named Wilhelm was shot in the leg with an arrow. The sound department used a shriek of pain that had been recorded a couple years earlier in another film.
Since then, the scream has attained a sort of mythical underground cult status amongst film buffs and sound engineers. Here are two videos that relate the entire story of the Wilhelm Scream. First, the history of the scream:
And next, a video compilation of some of the 130+ films and TV shows that have used the Wilhelm Scream over the years:
So now that you know all about the Wilhelm Scream, you too will be able to bore your friends and acquaintances with this trivial bit of film lore!