Very simply -- Vomit.

Have you ever seen a dog eating vomit?

Usually refers to the vomit resulting from a full night's drinking, hence, being so drunk, one vomits in the street, and, being that drunk, one has usually acted very stupid throughout the evening. The phrase "A dog's breakfast" is usually attributed to the way one has acted prior to the resulting vomiting. Phrase popularized by the sit-com Kath and Kim (AUS).
Sharon was totally out of control at my bachelorette party -- she really made a dog's breakfast of herself!
by K & K FAN August 7, 2006
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"dog's breakfast," which has been British slang for "a complete mess" since at least the 1930s. While no one took the time to write down the exact origin of the phrase, the allusion involved seems to be to a failed culinary effort, perhaps a burned or botched omelet, fit only for consumption by the mouth of last resort, Fido. As a vivid figure of speech meaning something so fouled up as to be utterly useless, "dog's breakfast" can cover anything from a play plagued by collapsing scenery to a space mission ruined by a mathematical error. "Dog's dinner," which seems to have appeared around the same time, means exactly the same sort of disaster, but has the advantage of being attractively alliterative. Both phrases are heard occasionally in the U.S., but are more common in the U.K. and Commonwealth countries.
That bedroom looks like a dog's breakfast. Clean it up man!
by jorgepj September 16, 2006
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when something is done in a very poor manner it is said to be a dogs breakfast
you have made a complete dog's breakfast of this
by frankie fester January 20, 2006
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An unappealing mixture of many things... a hodgepodge... a disorganzined mess... but probably still usable (or consumable in the case of food.) From the idea that a dog will eat anything and feeding it a mixture of whatever is on hand. (Unappealing because only the dog finds its breakfast appealing... if you see or smell the dog food in the morning, as you're feeding the dog, it may well turn your stomach.)
Those contractors didn't do very good work and the made a real dog's breakfast of that job
by PlaceHolder June 17, 2004
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A phrase to mean something so messed up it should be revolting. It originated in England when dog owners let their dogs out in the morning to pee. The dog would often eat any puke that the previous nights drunks had left on the street.
This stew looks like a dog's breakfast but it tastes great!
by St. Peter Dickinson February 24, 2017
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The human brain and what it's worth, according to author Kurt Vonnegut.
How could he have figured it out on his own using only that dog's breakfast between his ears?
by J Mulkeen October 24, 2008
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When you're a in a mad morning rush & dont have time to clean your teeth/deoderise or shower. You only have time for what the dog would do before he went out bum sniffing for the day. A piss & followed by dipping your face in a bowl of water
I woke up at 8.55 & had to go straight to work. I'm proper stinking, cos all i had time for was a Dog's Breakfast
by scousedom July 4, 2011
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