sure thing

/SH UH1 R TH IH0 NG/
noun
  1. 1

    That which is certain.

    โ€œThat horse is a sure thing in the race at 3:30.โ€

interjection
  1. 1

    A polite reply to thank you.

    โ€œ"Thanks a lot for your help." / "Sure thing!"โ€

  2. 2

    An affirmative reply; yes; certainly.

    โ€œ"Can you finish by tomorrow?" / "Sure thing!"โ€

Source: https://en.wiktionary.org/wiki/sure%20thing