A cloud of gasses that escape the anus by passing by a fat turd on the way out and retaining the essence of defecation. Also referred to as PPFs

The steamy cloud of rancid ass-gasses left in a bathroom after dropping a hearty dougan. See also log fog.
Don't breathe through your mouth, bro. You'll get a mad taste of that log smog.
by Zero2None February 11, 2016
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A greasy turd.

Example:
"Dude, I ate so many Slim Jims. It was a whole Smog Log.
I took a fat Smog Log
by JustaStoner January 14, 2020
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