Somebody wouldn’t be seen/caught dead…
Definition 1 of 1
Pro Tip 1/3Strong Dislike
Use the phrase to express strong negative feelings toward something. 
He wouldn't be seen dead at a cheap fast-food restaurant.
Pro Tip 2/3Hyperbolic Expression
It's an exaggeration; not to be taken literally, but emphasizes the intensity of the dislike. 
She wouldn't be caught dead in a second-hand store.
Pro Tip 3/3Informal Context
The phrase is informal, more suitable for casual conversations than formal writing. 
My cousin wouldn't be seen dead at a karaoke bar.