What? What did you say?

Nothing

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

safety / good health / peace

What?, Huh?

safe and sound / (as the adverbial 無事に) successful without any problem

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

whatchamacallit, X

何: interrogative pronoun; what

何か: something