1. (adj.) When a woman drinks so much alcohol that an alter-ego germinates over the course of the evening and then emerges when she blacks out. Usually this personality engages in behavior(s) uncharacteristic of her when she is sober (e.g. shameless flirting, sexual promiscuity, killer wit, speaking in foreign tongues, attempts at deep conversations with domestic/wild animals, peeing on things, smoking weed/doing other illegal drugs, etc.)
2. (n.) The alter-ego of said woman.
1. "OMG you should have seen Milfred last night. Ya know, the annoying squeaky-clean bitch from physics lab? As soon as she got there, she SLAMMED the whiskey so hard she went katterton and popped 3 donuts, took bong rips, talked to Levi's sleeping cat for 45 minutes, then finally passed out in a yogic position on the futon. Someone posted pics on facebook."
2. "When I saw her she was fine, but katterton came out after Caesar arrived with the Patron...I'll give you three guesses as to what happened."