I've never heard of it either. I've never heard of "Yekkes", and an inquiry to the "oracle" of Google turned up that the word "Yekkes" is a "mildly DEROGATORY" term applied to Jews of German extraction.
That lends more credence to it being a BOGUS entry, period.
Wikipedia was the source for my discovery that Yekkes is a derogatory term!
Sumptin' ain't kosher 'bout all this.
here is the wiki entry for Yekkes:
The term yekke (adjective: yekkish) (alt: Jecke or yecke) is a generally jovial, mildly derogatory term used to refer to Jews originating from Germany or adhering to the Western-European minhag. The word itself stems from a coagulation of Hebrew and Yiddish, loosely meaning "jacket". (Note that the similar-sounding Jacke does mean jacket in standard German.)
The title originates from the cultural differences in dress that developed between the more westernized Western European Jews who traded in the more traditional long coats for shorter "jackets" while the outer clothing worn by the Eastern European Jews was typically "longer" (such as bekishes.). The term is often used in a slightly derogatory or cynical manner, although it is also used as a badge of honour. It is used mainly in reference to the German Jews’ legendary attention to detail and punctuality. This sense for detail extends into the strict adherence to minhagim (religious customs, especially when pertaining to the synagogue service). Oberlanders—Jews originating from parts of Austria, the Czech Republic, and Slovakia—are often confused with yekkes due to similar minhagim.
I'll do some investigation. I never heard of any such custom in Judaism, and I strongly suspect it is as bogus as the sex through the hole in the sheet rumor that appears to have spread in Yahoo. ( Snopes even has a page dispelling that one it was so widespread )
Hmm..perhaps Snopes already knows about this one? I'll be back with an edit if I turn up anything one way or another.
Right now, I'm doubting the veracity of the entry.
Shalom
EDIT: THUS FAR After "Googling" terms such as German Jewish burial customs socks..all I'm turning up is that mourners who sit shiva may not be wearing shoes but in stocking feet at the home...and of course the Wikipedia article that is the source of your question. And I'm turning up THIS very question! The only two sources for any such "burial custom" of German Jews amid many pages mentioning Jewish burial customs.