the shirt off back

the shirt off (one's) back

Anything or everything one owns or has to offer. Those contractors will take the shirt off your back if you hire them. I mean, I paid them an exorbitant amount of money, and look at the shoddy work they did! I'm not surprised that Tammy loaned you money—she would give you the shirt off her back if you needed it.
See also: back, off, shirt
Farlex Dictionary of Idioms.

the shirt off (one's) back

Slang
The maximum one is able to give or lose: The only thing those swindlers didn't take was the shirt off my back.
See also: back, off, shirt
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • the shirt off (one's) back
  • the shirt off somebody's back
  • the shirt off your back
  • have the shirt off (one's) back
  • would give (someone) the shirt off (one's) back
  • I see what you mean
  • give (someone) the shirt off (one's) back
  • give the shirt off back
  • give the shirt off one's back
  • button-down