It's very similar like pwning a noob, "Shitting on Noobs" is the complete domination of one to multiple player(s) and metaphorically dumping on the player when the "dumped-upon" player has been terminated (Shitting on noobs is usually done on the Halo Multiplayer matches on Xbox live)
<Mahamed> That's so cheep, how the fuck did that happen.
<Jamal> Damn sasuke, I'm shitting on these noobs. WHERE'S MY DOUBLE, THERE IT IS.
<Mahamed> Damn, your having diarrhea on these niggas