In the multiplayer PC game Starcraft 2, cheese is a tactic or strategy that is considered to be overpowered and is not sportsmanship-like. It is used in a derogatory fashion by players, Youtube commentators, and tournament announcers in South Korea.
The exact classification of cheese can vary, but most forms of cheese are obnoxious "in your face" tactics that annoy the opponent and lead to victory within the first 5 minutes of the game. In general, it is impossible to counter a cheese tactic unless you scout the opponent's base. Most cheese strategies do not use the game's intended "combat" units. I.e. the SCV construction unit is intended to harvest minerals, not lead an assault into the enemy base.
Cheese is most commonly seen in the lower brackets of Starcraft 2. Most lower bracket players do not scout and leave themselves vulnerable to cheese. As players become more adept at the game, they begin scouting and will move into higher brackets.
The newer forms of Cheese such as the SCV bunker rush were first used in official South Korean tournaments. The strategies were then posted onto Youtube and copied by American Starcraft players.
A few popular cheeses are:
Void Ray Rush
SCV Bunker Rush
Planetary Fortress Rush
Photon Cannon Rush
Guy 1: "I was about to win the game, but then he rushed me with void rays."
Guy 2: "Fucking VR cheese"
Commentator 1: "And Boxer wins the tournament with his trademark Bunker Rush!"
Guy 1: "Only noobs
use VR cheese."
Guy 2: He only won because he cheese'd!