ten-four

10-4

OK; all right. Used to indicate affirmation or acknowledgment. The phrase comes from CB radio, which was commonly used (especially by truck drivers) before the proliferation of cell phones. A: "I'm going to pull over up ahead." B: "10-4."
Farlex Dictionary of Idioms.

ten-four

and 10-4
interj. okay. (Citizens band radio.) Ten-four, old buddy. I will do that.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • 10-4
  • as one does
  • eggs is eggs
  • All-y all-y oxen free!
  • damn well
  • by half
  • a cold day in Hell
  • (one's) best foot forward
  • best foot forward
  • Caturday