Pronounced like "ying-yang" without the "yi" at the beginning of the word hence the apostrtophe (') beginning the word as not many words in the english language start with the "ng" sound. The last syllable is just "yow".
1) n. extremely non-plussing information
2) n. an extremely non-plussing person
3) excl. a perfect response to such non-plussingness
1 "Man, that guy's just full of 'ngyangyow!"
2 "man, that guy is such a 'ngyangyow!"
3 Jack:"Dum-de-dumm blah blah... I'm a butt-sniffing circus bear." Buddy:"...'ngyangyow."
As an exclamation, it is also quite handy/appropriate when walking around someone just standing in public for no apparent reason. Like a person (who gives an impression they most likely don't understand the local language very well) at your grocery store, half blocking the entrance/exit. When you walk around them instead of saying "excuse me!", you give an understanding nod and say "...'ngyangyow."