I couldn't help but notice the sudden frequent occurence of the phrase "Yiddish Cup." Since Yiddish is my business, I had to find out what it was all about.
Turns out, it's one of those new-fangled "internet fads." I'd post a link to a place you could read about it, but you'd probably be better off doing your own research. I'll summarize it briefly:
Two online humor websites had a dispute over content ownership. In the course of increasingly heated exchanges and actions, Neil Bauman, an executive at one of the websites, emailed Max Goldberg, owner of the other website, accusing him of having "lost possession of [his] Yiddish cup." When this email was made public a few days later on January 10, 2006 (yes, just a week ago as of this writing) it created a sensation, and the absurd, even Dadaist ring to this insult led people to try and incorporate it in any way possible into their writing, correspondence, etc.
What strikes me about this story, other than how astonishingly quickly an internet fad can develop and spread, is that no one seems to have figured out the origin of the phrase "Yiddish cup." Since I know Yiddish, however, I knew what Bauman meant immediately. So here I will reveal it for all the world to see what the heck Bauman meant by "Yiddish cup."
Bauman is alluding to a Yiddish phrase, "yidisher kop," (it varies slightly in different dialects, and "yidish kop" is one such dialectal alternative) which literally means "Jewish head," and figuratively means "innate intelligence." There is a related expression, "goyisher kop," (gentile head) that means, not surprisingly, "innate stupidity." Thus Bauman's jab implies that Goldberg is not using the intelligence inherent in him as a Jew. It's a clever move on Bauman's part, at once insulting him and yet invoking a sort of cameraderie via their shared Jewish background.
Don't be too shocked by the overt bigotry of these phrases; every culture on Earth has at some point decided that it is superior to all others; why should Jews be an exception? You don't have to like bigotry, nor, of course, should you, but our outrage at the presence of bigoted sentiments in the traditional stock phrases of a given language should be minimal.
Finally, it's sort of a shame that this phrase is not, in fact, as nonsensical as it seems; I'm a firm believer in the dictum "No sense makes sense." We live in an absurd universe; thus there is a deep truth and strange beauty to absurd, nonsensical phrases and utterances, but this ain't one of 'em.