From Liquipedia Starcraft 2 Wiki
The StarCraft community has, over the years, developed a certain manner of conduct that players respect and abide by as a sign of good sportsmanship and respect to your opponent.
 Good Etiquette
Abiding by these standards and acting as is decorum is generally referred to as good mannered[sic] (or gm). It is common to tell your opponent "glhf" (good luck, have fun) before or as the game starts and a game is conceded when a player surrenders by typing "gg" (good game) or one of its variants, as a compliment of the opponent's good play. The player will then immediately leave the game. This is obligatory in professional matches in Korea and is also mandatory in some foreign tournaments. The winning player will type "gg" back as a sign of mutual respect. Good mannered players will be respected by their peers.
 Poor Etiquette
Breaking this etiquette, or simply indecent behaviour, is often referred to as bm (bad manner[sic]). Offences, in order of increasing severity, include:
- Not gging before a loss - You do not submit to your opponent's play and leave in a spiteful manner, sometimes interpretable as a ragequit. Leaving without gging shows an unsportsmanlike lack of respect for your opponent.
- Offensive Buildings - When your victory is 100% ensured, you build a townhall where your opponent can see it, for example, in his base. This is a rude way of saying "you've lost", but it is allowed in promatches. Usually it's a townhall to show how much money the winning player has. Alternatively a player builds buildings to spell out words or symbols on the map - though this is usually triggered by:
- Not leaving the game - When you know you have lost the game, you should leave. Dragging out a game by not leaving is both annoying and rude to players and observers. Terran non-leavers are known to float away their buildings to draw the game out even further. A variant is calling gg and then not leaving, which is disallowed in most tournaments. Trying to do a last resort attack after typing gg, hoping your opponent isn't paying attention thinking he got the win, is even more deplorable.
- Talking in order to distract your opponent - Light-hearted trash-talk and banter is usually encouraged, but talking or asking question with the intention of throwing your opponent off his game is a low blow. Kespa-regulation forbid talking in games entirely.
- Abuse, cursing, vulgarity - Don't insult your opponent after a loss.
- Offensive GG - Typing in the gg "for" your opponent, basically indicating the game is over. Very rude behaviour that is frowned upon severely.
- Spoofing Server Messages - Typing in "Player has left the game" when it is clear that Player is about to lose, in an attempt to trick the opponent into disconnecting under the assumption that they have won.
 Sportsmanship in Korean Progaming
- Leaving without GG is frowned upon but not officially punished.
- Building offensive buildings are allowed, demonstrated famously so by Much, MC, and Jaedong
 Usage of "Manner"
- Adjective - (with OBJECT) - A "Manner ((Building Name))" (ex. "Manner Nexus", "Manner Hatchery") is a building created in an obvious fashion at the loser's base to show the winner's dominance in the match. This tells the losing player how much money the winning player had when he lost. Usually expensive or redundant buildings are used such as creating a massive amount of Dark Shrines. "Manner" can also be used with other actions such as "Manner cheering" (using the cheer command in the losing player's base). Also see Manner Pylon.
- Adjective - (with PERSON) - Calling someone manner (ex. "ThorZaIN is so mannered") means that he acts respectfully in all showmatches, doesn't badmouth his opponents, and never shows rage or foul-mouthed behaviors.
- Infinitive - Telling someone "To manner (up)" means "to behave" or "To act with respect" (ex. "Manner!", "Manner up or leave").
- ↑ http://www.teamliquid.net/forum/viewmessage.php?topic_id=163692
- ↑ Boxer vs Junitoss on Forte - Boxer types "Base too small T_T" (transl.) in this game, leading to Kespa's decision to forbid in-game talk.
- ↑ IdrA vs Tarson on Medusa (open in VLC/Gom or similar) - Superdanielman on a diatribe on IdrA's bad manner.
- ↑ Much takes revenge on FBH for dancing around Much's teammate Savior in an earlier game.
- ↑ http://www.teamliquid.net/forum/viewmessage.php?topic_id=202507¤tpage=156#3120
- ↑ http://www.youtube.com/watch?v=wcE3gWHt-hc Jaedong BMs Firebathero