Dean- Paranormal Activity 1-4. It was a marathon kind of night.
Sam- Friday the 13th. You both waited for a Friday the 13th before watching Friday the 13th, you both thought it would add to the suspense.
Castiel- I Know What You Did Last Summer. You watched it one night when you were sick, he cuddled with you and let you squeeze his arm every time a scary scene would happen.