+1
Taxidermia (2006) really spun me around from beginning to end. It wasn't just what was depicted on the screen, it was how it made me feel while I watched it. Quite indescribable.
Special mention was while I was watching Mama (2013) in the theaters. This wasn't really because the movie was surreal in and of itself, it was actually because there was a family (with children) watching it, and very few others. They were acting very strange the entire time, like standing up and shifting around in the theater. Also, there were odd people coming in and just looking around. To this day, I still feel as if we were being messed with the entire time.
Now, I recognize that it sounds as if I was overreacting a bit. However, my girlfriend at the time was the one that mentioned it before I could, and weird things would seemingly happen during key points in the movie.