What does “bupke” mean?

If it's any consolation, Yoichi Oishi, the various forms of bupkes were not widely used and understood in the English-speaking world either, until a few decades ago. Here are the first readable/intelligible occurrences of each spelling of the word that a Google Books search finds:

bobkes: From Charles Angoff, In the Morning Light (1953):

"As bad as that," asked Moshe.

"Eh, we do get an order for a suit or two from some old customers, customers I myself got. Some alterations, some new suits. But it's all bobkes (peanuts). Not enough to pay for the gas and electric bills. Maybe it pays for the rent, maybe it doesn't, I don't know. I don't figure any more."

bubkes: From Donald Wayne, Flowers in the Valley (1937) [snippet]:

"Your dollar is still fifty-nine cents, whether you like it or not."

"Ah, bubkes," the man in the chair said, removing his cigar. His name was Spingarn and he was a tailor's cutter, short and fat, with small puffed eyes that gave him a sleepy greasy look.

bubkis: From Maxwell Bodenheim, Duke Herring (1931) [snippet]:

"What's that rag doing over there on the armchair?" he asked. "Don't tell me you go to the synagogue, Madge. Hot bubkis, that would be irony steaming from the water-closet. But now that I think of it, it's funny I never noticed that eyesore before."

bupkes: From Gilbert Rogin, What Happens Next? (1971) [snippet]:

"Do you think it distracts from my having next to bupkes on top?" Miles said. He took his hands off the wheel and, thrusting his head at me, grabbed most of his hair in two handfuls and violently parted it, disclosing his wan crown.

bupkis: From The New Yorker (1942) [snippet]:

"Wossamatta wichoo?" he wrote from Miami Beach this February. "You ain't got no conegshins in Flodda? A fortnight awready I been here and wos happening? Bupkis. A press agent like I got shouldn't happen to a dog-eared edition of 'Little Dorrit.'

bupkus: From Arnold Kanter, The Secret Memoranda of Stanley J. Fairweather (1981) [snippet]:

16.3 A resigning Partner shall be entitled to bupkus.

Meaning of the Term

With regard to the meaning of bupkes in Yiddish, several sources have fairly precise opinions. From Abbott J. Liebling, The Wayward Pressman (1947) [snippet]:

The high total may be explained by the circumstance that there is no Newspaper Guild minimum wage for columnists. Many of them work for bubkis (beans), as the boys say, either because they want the publicity for use in another profession (the stage or radio) or in the hope of catching on and getting a profitable syndication.

From Leo Rosten, King Silky (1980) [snippet]:

bupkes!: Nuts! Actualy, bupkes (or bubkes) means "beans," but it is about anything that's not worth a bean.

From Michael Gold, Jews Without Money (1930) [snippet]:

There is no baby in there, but a big pot full of hot black-eyed beans. "Bubkes!" she wails in a sort of Chinese falsetto, "buy my hot, fresh bubkes!' We forget the dancing, and remember the pennies burning a hole in Joey's pocket. We order some bubkes.

From Midstream; a Monthly Jewish Review (1979) [snippet]:

My grandmother donates to good causes. "Two Jews, three opinions," my grandfather says. "What will she get for it?" Only bupkes—"chick peas" in the old country. My grandfather is his own good cause.

"Bubkes" is actually a Yiddish word, and in this context has the same meaning as "nothing".

They took two months to give me nothing. But to give me nothing, they were required to invoke a FOIA exemption.

Pages 593-604 in the following book sets the record straight on the origin of the Eastern Yidish count noun באָבקע (bobke) ‘pellet of goat dung; pellet of sheep dung; small piece of any kind of excrement’:

Gold, David L. 2009. Studies in Etymology and Etiology (With Emphasis of Germanic, Jewish, Romance, and Slavic Languages). Alicante. Publicaciones de la Universidad de Alicante.

In brief, that count noun was back-formed from the Eastern Yidish plural noun באָבקעס (bobkes) ‘small pieces of any kind of excrement’ (as in ציגענע באָבקעס tsigene bobkes ‘goat dung’ and שעפּסענע באָבקעס (shepsene bobkes) ‘sheep dung’), which comes from the Polish plural noun bobki ‘small pieces of any kind of excrement’ (with replacement of the Polish plural ending -i by the Eastern Yidish plural ending עס [-es]).