Crocker's rules, named after and framed by Lee Daniel Crocker, is a social communication protocol or etiquette to reduce emotional impact on debate. Crocker was an early contributor to Wikipedia, and, with Larry Sanger, Fred Bauder and others who chose to contribute pseudonymously or anonymously, helped to form its rules to maximize objective reporting.
By declaring commitment to Crocker's rules, one authorizes other debaters to optimize their messages for information, even when this entails that emotional feelings will be disregarded. The underlying assumption is that rudeness is sometimes necessary for effective conveyance of information, if only to signal a lack of patience or tolerance: after all, knowing whether the speaker is becoming angry or despondent is useful rational evidence.
Thus, one who has committed to these rules largely gives up the right to complain about emotional provocation, "flaming", "trolling", "abuse" (hopelessly subjective terms) and other alleged violations of etiquette. They give these rights up in the interest of effective debate.
In contrast to radical honesty, Crocker's rules encourage being tactful with anyone who hasn't specifically accepted them. This follows the general principle of being "liberal in what you accept and conservative in what you send".
Crocker emphasized, repeatedly, in Wikipedia discourse and elsewhere, that one could only adopt Crocker's rules to apply to oneself, and could not impose them on a debate or forum with participants who had not opted-in explicitly to these rules, nor use them to exclude any participant.
Combining Crocker's rules with the principle of content over community resulted in another related maxim or principle that "all users are trolls", meaning, no user has the right to assume intent nor label nor categorize other users by perjoratives whose sole purpose is exclusion rather than characterization of the actual bias in an argument. Some wikipedia users for instance chose to use the term "troll" in their user name, or to describe themselves as "pro-troll" or even "smug pro-trolling trolls", and to disdain any argument that the origins of any writing or argument ought to be investigated at other than face value. See also the history of anonymous political comment.