Town of Salem relies heavily on communication between players. Because the day and night phases of the game are fairly short, and a lot of evidence may need to be discussed in these short spans of time, abbreviations and acronyms can be quite helpful. Here is a list of common abbreviations and their meanings. Other variations can be used, but these are just a few.
Voting and canceling your vote twice - This is the sign for being blackmailed. Note: This won't work for a revealed Mayor if 3 or less votes are required to lynch, as a Mayor's vote counts as 3 votes, it may lead other Townies to actually lynch said player. Members of the Mafia can also use this to a certain player to indicate that player needs to be acted upon by a member of the Mafia, but this is rarely used.
Reveal or Die - When a player is suspected of being either an evil role or the Mayor, said player will be put on trial. If they do not reveal themselves as the Mayor, said person will be lynched.
Remember/Revive someone tonight - When somebody claims Amnesiac/Retributionist. If they do not remember or revive a role, they will be lynched.
GL - Good Luck (amicable thing to say at the start of a game).
GLHF - Good Luck, Have Fun (amicable thing to say at the start of a game).
inb4 - In Before. Used to essentially say something before anyone else, such as just after lynching someone in Ranked when there is a dead NeutralEvil role, yet someone was acting very suspicious, one might say, "Inb4 AnyJester".
MB/My b - My Bad.
Meta - Abbreviation of Most Effective Tactic Available (Used when discussing about tactics people may use, for example, "You know, claiming to be an Executioner is the new Godfather meta.")
MVP - Most Valuable Player. (Usually a compliment given to the player who was the most beneficial to the team)
Premade - Having entered the game together with a party.
TBH - To Be Honest (Normally used when defending on trial or building up an accusation early in the morning. Example, "TBH, there's got be 2 members of the Mafia left, and (insert name) has to be one of them.")
Theme - Usually said before the game starts in the Lobby, and typically has a reference or popular trend before it, such as "Superhero" or "Food." This means a player wants to have the other players choose a name that would be related to the theme.
Tldr; or Tl;dr - Too Long; Didn't Read (sometimes used when a Last Will is too long, and the player(s) don't want to read it).
TY/Thx - Thank You (usually said after one player has been satisfied by someone else, for example, "TY Doctor for healing me", or "Thx for reviving me Retributionist.")