[douche]

If you act like a total dickhead in real-life, you're apt to get your teeth knocked in, which tends to modulate dickheadsian behaviors.

[coredog64]

I would also add that it's easier to be a dickhead online. You don't have to be particularly witty in real-time, and once you've gotten a working schtick, what wit you do have can be replicated via copy-n-paste.