The Hebrew slang phrase ma pitom מה פתאום is used to express surprise or incredulity:
מה פתאום אתה נוסע ליפן? - Mah pitom atah noseyah l'yapan - "Why in the world are you going to Japan!?"
A: Are you worried about traveling to Turkey?
B: Mah pitom! (Don't be silly!)
A: "You just stepped on my foot!"
B: Mah pitom! (No way!)
The proper response in this case is ken nachon כן נכון - "Yes you did!"
(Steg points out that this is the type of dialogue between God, Avraham and Sarah in Bereshit 18:10-15.)
What does this phrase mean? Literally, ma means "what", and pitom means "suddenly". However, "what suddenly" doesn't make much sense (in English or in Hebrew), so we need to find the origin of the phrase. Rosenthal writes that it is a loan translation (calque) from the Yiddish vos plutsem וואס פלוצעם and the Russian chego vdrug. I asked some Russian speaking friends about chego vdrug, and they told me that:
The best way to translate this phrase is probably "why all of a sudden" or "why now"So an original meaning of "Why suddenly" makes more sense. As far as the Yiddish, vos means "what" and plutsem is "suddenly". (It comes from the German plötzlich, meaning "sudden, abrupt" which derives from platzen, "burst". This is the source of the Yiddish word plotz - "to burst, explode - from strong emotion.) However, the meaning is clearly, "why suddenly". Professor Nissan Netzer (author of the book "Hebrew in Jeans - The Image of Hebrew Slang", which I'm currently enjoying) has confirmed to me that a better adaption into Hebrew would have been "lama pitom" למה פתאום.
chego in this case is why
vdrug: at this moment, suddenly
Both English and Hebrew have many Yiddish calques. Many expressions in English, such as "get lost" or "enough already" are borrowed from Yiddish, and perhaps aren't recognizable as such today. Hebrew is even more influenced by Yiddish - Netzer fills pages 212-230 of his book with loan translations from Yiddish to Hebrew.
Clearly, "what" and "why" are closely related. "What for" means "why". After thinking about it for a bit, I think I found an English loan translation from Yiddish where they replaced "why" with "what" - Alfred E Newman's famous catch phrase in Mad Magazine - "What, me worry?" The creators of Mad Magazine were very much influenced by Yiddish, and I'm guessing that phrase really means "Why should I worry?".
It turns out that the founder of Mad Magazine, Harvey Kurtzman, went to Camp Nitgedayget - "Don't Worry" in Yiddish. In the book Messiahs of 1933: How American Yiddish Theatre Survived Adversity through Satire, Joel Schechter writes :
Mad's motto, "What me worry? I read Mad," transformed the Yiddish summer camp's name into a formula for nationwide comic relief from pressures to conform during the 1950s. Paul Buhle reports that Kurtzman attended Camp Nitgedayget in the thirties; perhaps this Mad man's satire of consumer culture and American icons was influenced by his summer days at Camp Don't Worry - certainly by the name of the camp.And if we look at one of Kurtzman's early Mad covers, perhaps he knew the phrase vos plutsem as well...