What? What did you say?

Nothing

what / that thing (used in place of words you can't remember at the moment.)

What?, Huh?

(deictically) that place, area, or part over there (far from the speaker and the addressee) / (deictically) that organization or team over there (far from the speaker and the addressee)

(adverbial particle, dismissive, derogatory) emphasizes disgust, contempt, or otherwise negative feelings of the speaker: whatever

whatchamacallit, X

何か: something

何: interrogative pronoun; what

何者: someone; anyone / 何物: what