Disemvoweling is an online moderation technique intended to discourage trolling, by removing all the vowels from posts deemed unsuitable. The signal-to-noise ratio is thus improved as disemvoweled comments are easily spotted by users and can be skipped over. The same is even more true of simply deleting posts, but disemvoweling has advantages if there is likely to be disagreement between the userbase and moderators as to what content is appropriate. A disemvoweled comment can still be deciphered with effort, which helps establish community standards for what will or won't be accepted; moderations also becomes more transparent, and overly zealous admins can be challenged on their decisions. Further, a 'delete-or-keep' approach can give a false impression of respectability, as only acceptable contributions survive the cut; with disemvoweling, persistent trolls will end up with a visible track record of their antics.
The technique was declared one of TIME's best inventions of 2008, despite its use for comment moderation as early as 2002 by Teresa Nielsen Hayden- now community manager of Boing Boing, where it is also implemented. As we have a writeup for disemvoweled from 2000, the play on words, albeit in a slightly different context, is older still. Of course, the general idea of stripping vowels dates back to the prehistory of computing, as demonstrated by the naming of UNIX commands such as mv, cp and rm to save precious typing time, or my own mangled username to meet primitive 8-character limits.
Although programs for automatic disemvoweling of text now exist - Teresa used to perform the process by hand! - it's still a tool for use by moderators, rather than a replacement for them. In particular, it's of no real merit as a spam filter; although it'd be amusing to force link spammers onto vowel-less domains, it's clear from a random sampling of my junk folder that they're happy for their messages to be barely legible already. Whilst leet-speak would technically dodge the effects of disemvowelment, littering your text with numbers in place of vowels does just as good a job of marking your comments as entirely ignorable- and leaves them vulnerable to other measures such as stupid filter.
However, If you're being trolled in Hebrew, then I guess you'll have to think of something else.
5 Ways to Stop Trolls From Killing the Internet (Cracked)
Disemvoweling- TIME's Best Inventions of 2008 (TIME)
How To Keep Hostile Jerks From Taking Over Your Online Community (Information Week)