Folks who use Twitter a lot have probably run into their fair share of hashtags - topics preceded with a # hash symbol, which Twitter users (and, now, Twitter itself) treats as "tags" - words around which topics are organized. For example, conservatives on Twitter often organize their conversations with the #TCOT (Top Conservatives on Twitter) hashtag. During the unrest following Iran's disputed election, supporters used the #IranElection hashtag to rally support for the protesters and track the situation on the ground in Tehran. Anyone can use hashtags, and Twitter (as well as several third-party Twitter applications) keeps track of them and the conversations in which they're used.

Hashtag hijacking is when Twitter users begin to use a hashtag in their tweets in such as way as to subvert its original usage, either filling the discussion surrounding it with meaningless chatter or co-opting it completely. When it happens to you, it's incredibly irritating - in its best case, it's the Twitter equivalent of someone constantly turning the topic of conversation toward whatever they want to talk about. In it's worst form, it's like having someone sit in the back of a support group, heckling people.

Although it can sometimes be frustrating to watch a bunch of people you strongly disagree with holding a conversation, hashtag hijacking is the worst possible solution; it's bad for everyone and it undermines the fabric of common courtesy upon which Twitter was built.

Take, for example, @Papa_Shango, who recently decided to start using the #militarymon hashtag (which was created by the spouses and families of soldiers deployed abroad for the purposes of building and organizing support) for his own purposes - like comparing soldiers deployed in Afghanistan to Nazis and mocking the families of those who had lost loved ones in foreign wars.

Although, in the above case, @Papa_Shango was within his rights to use the #militarymon hashtag ("It's a Monday," he wrote, "and I'm discussing the military. What's wrong with that?"), his actions were nonetheless rude and highly antagonistic, actually hurting the image of the cause he was attempting to promote - world peace. Rather than creating a new hashtag to criticize foreign wars, or finding a hashtag around which conversations like his would be appropriate, he instead chose to use the #militarymon hashtag, knowing that his tweets would be seen specifically by the people most likely to disagree with him and most likely to be personally hurt by the things he had to say.

It's the Twitter equivalent of hitting below the belt, and it's a disturbing trend that seems to be happening more and more. The open nature of discussion on the microblogging platform means that users can pick fights faster than ever before - and that seems to be what a small but vocal minority of users are interested in doing. The problem is that once the Pandora's Box of hashtag hijacking has been opened up, it's difficult to close again. If the opponents of ideas spend all of their time sabotaging their rivals hashtags, they won't have any time to build a solid following of their own, and they'll break down the very fabric that hashtags hold together - the ability to organize tweets on a topical level. Once hashtags can't be relied upon to be an accurate indicator of the kind of conversations users will find surrounding them, the entire system of hashtags will have been broken, possibly irrevocably.

In situations where users disagree with the followers of a particular hashtag, the best course of action is to simply find their own supporters and rally them around their own hashtag. Everyone should have the right to discuss what they want on Twitter without having hecklers screaming at them from the back of the room - including people you might completely disagree with. If you try to remove the ability of your rivals to hold conversations, you shouldn't be shocked when you discover that your ability to hold a conversation has been similarly crippled. Once that starts happening, Twitter breaks down into an all-out battlefield and nobody can get anything done anymore.