Once you hear this - you won't be able to un-hear it.
You've heard it before, though. More than once. Maybe even hundreds of times. It's a stock sound effect called "Wilhelm Scream" and was first used in the 1951 western Distant Drums.
It is named after the character Private Wilhelm from 1953's The Charge at Feather River, when it was apparently first pulled from the stock library at Warner Bros.
You've heard it in Star Wars, Indiana Jones, Warcraft, Toy Story - it's become a genuine in-joke. It's rumoured to be in over 360 productions. It's a meme for film makers.
But not being able to un-hear it - that's a real curse. Sorry about that.