Plenty of horror’s scariest scenes are simply the result of a lot of off-screen hard work.

One of the most high-stress moments in Friday the 13th (1980) comes when the final survivor, Alice, is running for her life after finding many of her friends dead. While attempting to hide in a cabin, her friend Brenda’s corpse is tossed through the window by a masked killer.

Well, behind the scenes, that “body” was actually the film’s makeup artist, Tom Savini. Savini previously worked on films like Dawn of the Dead (1978). However, Friday the 13th offered Savini a rare opportunity to make an on-screen appearance, though many wouldn’t recognize him.

“Yeah, I put on the wig and the dress and just crashed through the window,” said Savini, according to Making Friday the 13th: The Legend of Camp Blood by David Grove. “I wasn’t thrilled about it, but it had to be done. I think that might’ve been the last night of filming because we were really under the gun to do it.”

Time constraints aside, director Sean Cunningham understood that a horror movie is nothing without a good death scene.

“We tried to exploit that in Friday the 13th,” said Cunningham. “We tried to draw out the kill scenes and make the audience very nervous. Even worse, the character doesn’t know that he’s going to be killed. It worked very well.”