expression
who cares?; see if I care; who knows?; how should I know?
Emphatic dismissive expression: the speaker strongly denies caring or knowing. Often used in casual, sometimes confrontational speech. The ものか ending adds a rhetorical, defiant tone.
あいつのことなんか知るものか。
Who cares about that guy? / See if I care about him.
そんなこと、知るものか。
How should I know about that? / Who knows about that?