How should I know?

How should I know?

I don't know; I'm not the person who can answer that question. Often expresses the speaker's annoyance or frustration. A: "Is Nick coming tonight?" B: "How should I know? He hardly talks to me anymore." A: "Whoa, what happened in here?" B: "How should I know, I just got home myself."
See also: how, should
Farlex Dictionary of Idioms.

How should I know?

 and Don't ask me.
Inf. I do not know.; Why should I be expected to know? (Shows impatience or rudeness.) Bill: Why is the orea called the killer whale? Mary: How should I know? Sally: Where did I leave my glasses? Tom: Don't ask me.
See also: how, should
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.
See also:
  • here we go again
  • (just) as I expected
  • as I expected
  • DGAF
  • arty
  • arty-farty
  • be a thorn in (one's) side
  • be a thorn in your flesh/side
  • Would it kill (someone) to (do something)?
  • It sucks