In a total state of mammal-ness. Way too fucked up. To operate at only the most basic levels of humanity. Derived from the word mammal. Under the influence of any booze or drugs to the most extreme limit. Similar to being pissed (UK) or shitfaced (US).
"Dude, I was so fucking Mammied last night! It was awsome." or "Let's get mammied!" or "Fast Ed, why do you insist on getting so mammied every night? Look at yourself, your a complete mammal!"