Used in jest when an overweight and obnoxious girl enters the room and you want her removed. Alludes to whaling harpoons.
Or, simply, a joke to crack when a large woman is observed.
Charlie: Oh my god, that is horrid! We're gonna die!!!
Dane: She'll eat us alive, for sure! AAHH!!
Keith: Nonsense! The harpoons, Charlie! Man them at once!
Alex: "Once you launch the harpoon, you can't get that shit out!"