To plow a gagger is slang for snorting a large
line of Cocaine or Crystal Meth. Plowing comes from the size of the
line being too large to snort at a normal
speed so the user accidentally 'plows' the line with the straw, moving the drug rather than snorting it up the tube. Gagger comes from the action of gagging that is often associated with snorting a line of this magnitude.