The pawn was a chess piece players used when playing chess. Each player could use up to eight pawns in one game, either coloured black or white.
Artie Maitland, while playing chess with Porridge, moved one of his pawns to f4. However, the move was the typical opening for a fool's mate, allowing Porridge to check and subsequently checkmate Artie's king in two moves with his queen, ending the game in a decisive victory for Porridge. (TV: Nightmare in Silver)