well, barnyard: some eggs (in most cases) that are anything and everything then you can put in your bator and you get a mix... barnyard cross, well the the same as stoopid said...
Barnyard crosses don't need to be such a mutt that even an experienced person can't tell the parentage, they're just a cross of whatever. Even a first generation cross of, say, Cochin x Sebright, can be a "barnyard mutt," because they are essentially a mutt.