You had just become aware of a curious, unexplainable, epidemic mass hysteria.
5 seconds sound clip from the Invasion of the Body Snatchers (1956) movie soundboard.
You can hear this line at 00:34:34.330 in the Blu-ray version of the movie.
Quote context
[...]
- It was there half-hidden by that blanket.
- You said you saw it there just now.
- Why did you come here tonight?
- You'd seen a dead man at Jack's, an average-sized man.
- The face in death was smooth and unlined, bland in expression, which often happens.
- You had just become aware of a curious, unexplainable, epidemic mass hysteria.
- So your mind started playing tricks, and reality became unreality.
- The dead man became Jack's double in your eyes.
- Look come off it will you, Dan.
[...]