Be scared/bored witless
Definition 1 of 1
Pro Tip 1/3Intensity Emphasis
The phrase intensifies the feeling of fear or boredom beyond the ordinary level. 
When faced with the haunted house, she was scared witless.
Pro Tip 2/3Colloquial Usage
It's informal and best used in casual conversation or creative writing. 
During the dull lecture, he whispered to me that he was bored witless.
Pro Tip 3/3Hyperbole
This phrase is a hyperbole, exaggerating for effect, not meant to be taken literally. 
At the sight of the spider, I was scared witless.