Similar to the Vulcan, and the shocker. The rusty chainsaw is the act of penetrating a womans' anus with the entire hand very rapidly. The remnants left on your hand after the act give the "rusty" appearance.
My wife pissed me off the other day so, as revenge when we were going at it doggystyle I gave that bitch the ol' rusty chainsaw. That's why I'm staying in the hotel tonight.
When in the act of using anal beads on male or female. Ripping them out too fast results in a fecal splattering which gives it the name of the rusty chainsaw
the other night i gave my wife a rusty chainsaw and as punishment I had to clean that room for hours