The act of making up a word prior to finding a meaning or use for said word, and is a tactic often employed during games of scrabble.
Halvinating is itself a product of the process which it describes (but coincidentally this did not involve a game of scrabble, just a group of trashbags having dinner in a restaurant preceding an epic night out @ Lounge in Melbourne).
A: "Yeah! Triple bitches! SHACISM!"
B: "Dude that's not a word what the frack is that?"
A: "Hey man it *is* a word. It means...discrimination against SHAMANS!"
B: "Halvinating AGAIN!"