Internet acronym for Smash Left Wing Scum.
Bob: I saw this guy in a hybrid car today... and that's cool. I'm all for ending dependency on foreign oil and all... but he got too distracted whilst eating his tofu burrito and he hit an old lady. That old lady was my grandma.
Joe: That damn commie. That makes me want to go Smash Left Wing Scum (SLWS) and put some more carbon, a naturally occurring gas that plants breath, into the atmosphere.