Originally originating from the game Wide World (where when a 6 is rolled the players are moved on the weather vane across the board, invariably where they do not want to go), weathervaned means to be generally beaten, owned or pwned, often unexpectedly.
Jeff: I'm only one square away from winning
Andrew: (Rolling a 6) WEATHERVANED!!!!
Reginald: Hullo, may I join you in partaking in this game of basketball.
Jamaal: No. (Hurling ball in Reginald's face) WEATHERVANED!!!!!!11!one!