From the 1978 US television showMork & Mindy, where it was used as an alien greeting.Originally said by Oscar-Jack Klugman onThe Odd Couple in the episode "Psychic, Shmychic" in 1972.FromSanskritननु(nanu,“surely”) (vocative particle, implying kindness or reproach or perplexity).(Canthis(+) etymology besourced?)
For quotations using this term, seeCitations:nanu-nanu.
nánu-nánu