A conversation ender. Used at
the end of a statement when a person in the middle of a conversation wishes to stop talking about it immediately.
Coined from the TV show LOST, where at
the end of every episode, the word "LOST" flashes across the screen, ending the episode very abruptly or on a
cliffhanger.
Guy 1: "So I totally hooked up with that hot blonde last
night at the party. I wish I had gotten her
number."
Guy 2: "Dude, that was my
cousin. LOST."