somebody wouldn't be seen/caught dead...

wouldn't be caught dead (doing something)

Would never do the thing being discussed; would be horribly ashamed or embarrassed to do something. I wouldn't be caught dead wearing that shirt. You can burn it for all I care. She had always said she wouldn't be caught dead working for that company, but I guess everyone has their price.
See also: caught, dead
Farlex Dictionary of Idioms.

wouldn't be seen dead

or

wouldn't be caught dead

COMMON If you say that you wouldn't be seen dead or wouldn't be caught dead in particular clothes, places, or situations, you are emphasizing that you strongly dislike or disapprove of them. I wouldn't be seen dead in a black straw hat. The modern cowboy wouldn't be caught dead in such an old-fashioned place. There's many a dad who wouldn't be seen dead wheeling a baby in a pram through the park.
See also: dead, seen
Collins COBUILD Idioms Dictionary, 3rd ed.

somebody wouldn’t be seen/caught ˈdead...

(spoken) used to say that you would not do a particular thing because you would feel stupid or embarrassed: I wouldn’t be seen dead in a hat like that. She wouldn’t be caught dead in a place like this.
See also: caught, seen, somebody
Farlex Partner Idioms Dictionary
See also:
  • caught dead, wouldn't be
  • wouldn't be caught dead (doing something)
  • chisel
  • chisel out of
  • chiseled
  • cast (one's) eyes down
  • cast eyes down
  • your heart is in the right place
  • your, his, etc. heart is in the right place
  • one's heart is in the right place