The phrase "until the cows come home" just came up. To be more specific, I used it and my German girlfriend laughed and assumed that I had coined it myself.
A quick search on google found 16200 references. One of the first (
http://tinyurl.com/2kqxt) yielded the following:
"A long time, usually defining how late
someone might stay up at night or out at bars, nightclubs, discos etc. The origin of the phrase goes back to
a time when people were familiar with the time cows came home (in the very early morning... 4 - 5 a.m.) because they wanted to be milked."
My memory of the term, and its usage by my mother (who grew up on a dairy farm) suggests no such focus. I always understood it as being more or less equivalent to "until hell freezes over".
Redwine
Hamburg