While fucking your girl doggie style, you suddenly pull out for no apparent reason. When she turns around for an explanation, she notices you've jumped off the bed onto a skateboard, holding the mighty dildo-harpoon in hand, cocked and ready to spear her in the ass. You pursue her as she runs out of the house and down the street while yelling, "You're not getting away from me this time, White Whale!"
A refrence made about a overweight girl. But not as big as a beeps. When one has been deemed an ahab, generally the phrase "Grab yon spear" is shouted to tell inform those around of the ahab's presence.