I could care less

could care less

Does not care about something at all. The phrase is a colloquial version of "could not care less." Fine, I could care less what you do! Good riddance! You're going out with my ex-boyfriend? Great. I could care less.
See also: care, could, less
Farlex Dictionary of Idioms.

I could care less

verb
See I couldn’t care less
See also: care, could, less
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • could care less
  • see what I care
  • for all (one) cares
  • for all I care
  • for all I, you, etc. care
  • I couldn’t care less
  • couldn't care less
  • couldn't care less, he/I/she
  • less
  • see if I care