New York City term for trashy dim bulbs from Long Island -- hence the L-I in the term -- who invade Manhattan in droves every weekend. The opposite of, and a relaliation to, the middle-class snobs in the Hamptons who call City residents who vacation there in the summer "cidiots."
We decided to stay away from our favorite bar last weekend because when we arrived it was filled top-to-bottom with drunken, tubby lidiots acting obnoxious and picking fights with each other.
A person who chooses the wrong sized lid on a to go coffee cup. Either too small so it falls into the drink, or too big and it just sits on the top doing nothing. Once they realize it they say " I'm such a lidiot"