higgledy-piggledy
Concise Oxford English Dictionary © 2008 Oxford University Press:
higgledy-piggledy/hɪɡldiˈpɪɡldi/
▶adverb & adjective in confusion or disorder.
– origin C16: rhyming jingle, prob. with ref. to the irregular herding together of pigs.
'higgledy-piggledy' also found in these Oxford entries:

