何々
なになに · naninani · JLPT N2 · noun
What?
❓ なに (nani) = what; 何々 doubles it: 'what-what' = such-and-such, a vague placeholder for 'some stuff'
Reduplication: 何 (nani, 'what') repeated as 何々 signals 'so-and-so' or 'such and such'. The sound なにな (nani-nani) echoes the repeated word, like English 'whatchamacallit'.