What movie cliche do you find most annoying or grievous.

"Checkmate".

Whenever you see two highly intelligent characters having a dialogue battle of wit mirrored through a chess game and one suddenly checkmates the other to there complete supprise (and usually win's the argument of discussion at the same time).

Anyone who's familiar with chess typically knows most strong players see a losing situation well ahead of the actual checkmate and will surrender. In reality this cliche only works if the two characters are secretly awful at chess.

EDIT: Two offenses that come to mind are Sherlock Holmes: A Game of Shadows and The Avengers (no, not the Marvel one). both have scenes like. They further compound the lunacy here by having one or both characters play without even looking at the board.