When someone makes such a concerted contribution to a conversation or activity that they might as well have done nothing. Especially in relation to online conversation and the general laziness promoted by online anonymity.
Often used sarcastically.
Sometimes written non-contribution or (non) contribution
<Fred> Hey guys! What are you talking about.
<Sam> Josh and I are having a detailed conversation about the effects of global warming on Arctic Polar bear populations.
<Fred> Yeah, Al Gore has stinky balls.
*Fred has been kicked by Josh* (Kickmsg: Thanks for your noncontribution asshole!)