The Japanese have taken snowball fights to a whole new level and named it Yukigassen (雪合戦). The game is now played in tournaments around the world. The word Yukigassen can be translated to mean yuki (snow) and kassen (battle).
Short description of the game from wikipedia.org
“Yukigassen is a game between two teams with seven players each. The game is played on a court with certain measurements, and the winner is determined through rules made by the Japan Yukigassen Federation. It is similar to capture the flag; players are eliminated when hit with snowballs. Players wear special yukigassen helmets with face shields, and a set number of snowballs (90) are made in advance.