Wiktionary
n. (context Internet uncountable English) The disruptive act of posting a flood of articles to a newsgroup, the article headers having been falsified so as to make the articles appear to have been posted by people other than the true poster.
Wikipedia
Sporgery is the disruptive act of posting a flood of articles to a Usenet newsgroup, with the article headers falsified so that they appear to have been posted by others. The word is a portmanteau of spam and forgery, coined by German software developer and critic of Scientology Tilman Hausherr.
Sporgery resembles crapflooding, which is also intended to disrupt a forum. However, sporgery is not merely disruptive but also deceptive or libellous—it involves falsifying objectionable posts so they appear to come from newsgroup regulars. The purpose is not merely to jam the forum, but also to sully the reputations of its regular users by falsely signing their names to offensive posts.