Verb:
To search for any subject on Wikipedia prior to researching via a reliable source.
Also see wikiwacked.
Descriptive:
Of someone who's information is consistantly of low or suspect quality.
Eg: "Don't listen to that guy. He is totally wikiwacked!
If you don't really care about the validity of the info in your dissertation, just wikiwack the subject!
When an over zealous fanboy hijacks and changes information in certain wikipedia articles to defame, libel, or completely destroy someone.
This can also apply to anyone that randomly goes on wikipedia, chooses a random, non-protected wikipedia article, and edits it completely without anyone's consent.
In other words, people that get joy from editing wiki articles to fit their own destructive/sick goals.