Tell

A tell, or whisper, is a private message sent from one player to another, often denoted by the color pink in the chat window. This does not bypass ignore functionality, which means that the character being ignored will see a reply stating as such. It is also impossible to whisper opposite faction players.

PST
PST is an acronym for Please Send Tell. It originated from older online games, MUDs, and MMORPGs such as EverQuest, which used /tell to send private messages to other players. In World of Warcraft, it has come to be frequently mistaken for the interjection 'psst', due in part to the game's common use of /whisper. The latter meaning has become fairly widespread amongst players, occasionally leading to debates and disagreements over its proper grammatical usage (for example, "LFG, PST" versus "LFG, please pst me").