Android M is internally known as Macadamia Nut Cookie, but this means nothing
From the looks of it, Google is internally referring to the upcoming Android flavor as Macadamia Nut Cookie, or MNC. This name was spotted in certain code branches in AOSP, but what does this mean? Well, nothing, actually, as it only confirms that the real deal won't sport this arguably long and cumbersome to remember name in particular.
See, Google is obviously fond of three-word codenames for its major Android editions.For example, KitKat was rolling under the Key Lime Pie alias, whereas Lollipop was named Lemon Meringue Pie. Never before has a codename turned out to be the real name of the OS version, and Android M is unlikely to break this tradition.
Speaking of names, we have a handful of possible candidates. Your favorite turned out to be "Marshmallow", with "Muffin" and "Milkshake" being the runner-ups.