Disemvoweling
Disemvoweling (also spelled disemvowelling) is a technique used by forum moderators to suppress Internet trolling, vandalism, and other rude behavior in online discourse by removing all the vowels from the offending material. The disemvoweled text can still be read, or rather puzzled out; but it is clearly marked as deprecated, and is no longer susceptible to being automatically read by every passer-by who happens to glance at it.
This trick of removing vowels was invented by Teresa Nielsen Hayden in her weblog Making Light on 21 November 2002. Very shortly thereafter, the term "disemvoweling" spontaneously occurred to more than one person, the first of whom may or may not have been Arthur Hlavaty. Primacy cannot be determined. What is known is that Arthur Hlavaty was the first person to have used the term in print.
Disemvoweling has since turned out to be a surprisingly effective tool for maintaining order in online venues. For some reason, the fact that their text is still present, even in severely altered form, seems to baffle trolls' normal impulses. They are significantly less likely to re-post disemvoweled arguments than deleted ones. They may cry censorship; but since the other participants can, if they wish, puzzle out the original message, and see for themselves why it was disemvoweled, the troll does not get much sympathy. Also, disemvoweling gives the moderator the option of only suppressing the offensive bits of an otherwise valuable message. Not only does this preserve worthwhile material, but it makes it clear to everyone just where the line got crossed: a useful piece of clarification and public education. Finally, the disemvoweling convention can be used by the participants themselves, to preemptively disemvowel passages which may be somewhat offensive—though admittedly, self-disemvoweling is most often done for humorous effect.
In the years since its invention, Teresa Nielsen Hayden has spoken out in favor of leaving the letter "y" untouched when disemvoweling text. She gives two reasons. First, it is tedious to have to delete some instances of "y", but not others. The second and far more significant reason is that removing "y" can push the disemvoweled text over into true illegibility, at which point the technique loses many of the virtues discussed above.
A couple of programmers have written automated disemvoweling plug-ins to use with Movable Type. Bryant Durrell's shrpshr.pl removes the vowels from all comments coming from a specific IP address or addresses. Thomas Hassan's disemvowel.tar.gz lets the moderator zap specific individual comments. The two plug-ins, as well as other disemvowelling techniques, are discussed in the main body and subsequent comment thread of a "Making Light" post called Autodisemvowelling.
A note on the spelling: The word follows the standard patterns of English orthography; i.e., Teresa Nielsen Hayden spells it "disemvowelling" and Arthur Hlavaty spells it "disemvoweling".