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.
The act of inserting a female's entire hand into her vagina while engaging in anal sex, using her wrist/forearm as a means to alternately pull your penis more forcibly into her ass and push her hand more forcibly into her vagina.