I was too young to see The Exorcist when it came out in theaters. However, my mom and siblings went so I got to hear the tales of the horrors they witnessed. That was before pay-per-view so It would be years before I had a chance to see it.
I while ago I was curious about what a phenomenon that movie was back then, so I looked up some articles, news stories and archived videos. It was crazy how after the first few showings, ambulances had to be placed at theaters. People were fainting, throwing up, running out of the theaters and there were a lot of people that needed medical attention. It was definitely a barrier-breaking type movie. Now that stuff is just old-hat.