OK, I see this often in some forums, and just starting to see it here.
This is where someone posts in a thread that has potential for excitement, epicness, or plain FAIL.
The post adds nothing to the thread, but is simply someone saying "In before ". Why post at all? What does 'getting in' do for you if you're not adding to the thread?
This is one of the more annoying things I see on da Interwebzeez.