This phrase is in common use around the east anglia region, evolved from the word OK. The evolution of the word took place as follows: K>KK>OK>Okay>Kaky Coo. People often get the phrase Kaky Coo mixed up with the phrase 'Krappy Coo' meaning the opposite of Okay. A mix of Kaky Coo and the word Crap lead to to the invention of the phrase Krappy Coo. These days, the word Kaky Coo is in wide circulation.
Liam: You alright m8 x
Callum: I'm Kaky Coo m8 x
Callum: I'm having a big party later and there will be mosh pits there, you can come over if you want to.
Liam: Kaky Coo m8 x