Bog Fog

The smoke left over in a pipe or bowl after it has been hit. Generally, Bog Fog is left in the smoking device when the smoker does not uncover the carborator, or does not fully clear the smoke with their hit.

Tom: *passes bowl to Jim without uncovering the carborator.
Jim: "God damn it Tom, use the fucking carb. You keep leaving me Bog Fog.

Or...

Eddie: passing the bowl to Raymon without uncovering the carb. "Yo ray, theres not much left so I left you the Bog Fog."
Raymon: "Thanks Ed!" *hits bowl emphatically.