nanu-nanu

Etymology
From the 1978 US television show , where it was used as an alien greeting. Originally said by Oscar-Jack Klugman on "The Odd Couple" in the episode "Psychic, Shmychic" in 1972. from Sanskrit; nanu surely (nanu; vocative particle, implying kindness or reproach or perplexity)

Interjection

 * 1)  hello
 * 2)  goodbye