Dog's breakfast
Meaning
A mess or muddle.
Origin
This is a 20th century phrase. Eric Partridge, in the 1937 edition of his A Dictionary of Slang and Unconventional English lists it as "a mess: low Glasgow".
This is not to be confused with the the similar phrase - dog's dinner which, although coined around the same time, has a completely different meaning.
See also: the dog's bollocks.

