A wonderfully descriptive term for dog shit. Anyone who has ever observed a dog taking a dump will attest to the fact that they do look remarkably as if they are attempting to lay an egg.
Readers of the British humorous magazine Viz will probably already be aware of this expression, which is where I first saw it. I am pretty sure that's also where I first saw the white variety of dogs' eggs alluded to with something approaching nostalgia, along the lines of, "Whatever happened to white dog shit? I never see it any more."
It's a fair question; I vividly remember, in the dim past, frequently seeing white dog shit in the streets of London. At a certain point it simply stopped appearing, never to be seen again. A revolution in canine fecal fashion? Something to do with implementing new EEC standards? Who knows: but some of us still remember the good old days, when dogs' eggs came in brown and white.