I've been hearing flake and fake interchangeably for over 50 years....here's a source that thinks "flake" goes back to English naval power days...
Nautical Terms
I know there is a subtle difference in the words fake and flake...but to be honest...I'm not sure what it is any more....is one the act and the other the finished product as in "I am about to fake the line" and "that line on deck is flaked out"?
Either way both terms have been around....just most people are bastardizing at least one of them a lot.