I snuck into the theater to see the EXORCIST when I was 12 years old - I couldn't sleep for 3 nights.
Same here...my sister and I badgered my dad for 3 months to take us to see it...we were 13 and 14...he finally relented..and said if i take you you are going to sit there and watch it...we're not leaving early. That movie freaked us out! we slept together with the lights on for a month.
The book even scarier than the movie. Nightmares for weeks.