The act of posting news stories on the Chat forums, particularly either weird/unusual (“Lesbian mud-slinger sanctified by Pope in Zimbabwe”) or globally important (“US declares war on China!!”) ones.
News posting is considered a competitive sport by many, and indeed was portrayed as such in Luaky Commer.
The cardinal sin of News Posting is to post a story after it has already been posted - often about two days later. When this happens, it is traditional for the original poster of the story to post a link to their earlier post of it, accompanied by 'ahem!'.