Often used as an insult to describe a persons over the top fashion sense, this must involve a variety of mismatch colours .
It can also be used to describe most things with allsorts of random bright colours in it. Such as sick, girls face with too much make up on it, a bad painting, etc, etc…
A monkey's breakfast being an assortment ramdon fruits picked by monkey. Therefore, should only be for a monkey.
"Christ mate. You don't want to wear that out tonight do ya? You'll look like a monkey's breakfast!"
Dude! That bird over there has way too much make up on! Her face looks like a monkey's breakfast!!!