BM in chess is an acronym for Bad Manners. In chess, it means poor etiquette during a game. In this sense, BM refers to rude behavior such as making funny faces, talking loudly, or doing other things that don’t make other players happy and trying to annoy them. This is against the rules of chess and penalty points should be awarded for this behavior.
1) During the game, if a player is excessively eating or drinking, he/she will be considered to have committed BM, and penalty points shall be awarded by the arbiter.
2) If a player intentionally drops chess pieces from the table during the game then it also becomes BM.
3) If an opponent scoops up all the pieces from the board during a game, it is BM.
4) If a player jumps over the chessboard with his/her hands raised high then this constitutes BM and a penalty point should be awarded.
5) The opponent unintentionally knocking over pieces on the board is not taken as BM but if intentional, penalty points are awarded.
6) If a player distracts the opponent by saying anything, it is considered BM.
7) Sudden or unreasonable slamming of any chess piece on the board during the game constitutes BM and penalty points are awarded.
8) Chess pieces that are thrown toward an opponent are considered to be BM.
9) Any other rude behavior during the game is considered BM and penalty points are awarded accordingly.
10) When one gets up from the board without permission, it is also considered to be BM.
11) If a player spoils another’s game by touching his/her pieces then this too constitutes BM.
12) Whether or not it happens intentionally, if a player hits a clock to start or stop the time then also it is considered BM.
13) If a player makes an obscene gesture during a game, it becomes BM, and penalty points are awarded.
14) Intentional distraction of opponent by talking which may annoy him/her is counted as bad manners. If a player does this repeatedly, penalty points are awarded.
15) Once a player places the king on the side of the board, it indicates that s/he resigns and this is not considered as BM. However, if a player slams the king down on the board after resignation then it becomes BM.
16) Excessive banging of pieces before capturing them can be considered BM and penalty points are awarded.
17) If a player does not follow the proper timing such as making move before time control or exceeding time control then also it is considered BM.
18) A player who deliberately plays slowly in order to take advantage of his/her opponent committing BM shall be penalized according to the rules.
19) Making a move without the permission of an arbiter is also punishable as BM.
20) Any other behavior that does not make other players happy and tries to annoy them, is considered BM. When a player commits a single act of this nature he or she shall be warned, if repeated – awarded penalty points. If there are abusive languages used in a game, the player may lose by forfeit.
In short, when a player commits any poor etiquette during a chess match he/she is said to have committed BM and penalty points can be awarded by the arbiter.