Derived from "Shawshank" (i.e. "The Shawshank Redemption"), shankshawing is the process of slowly chipping away at a person until the ultimate goal is achieved.
Said "goal" is usually the love/affection of a person who is already in a relationship. First you become their friend, their shoulder to lean on when times get tough with their partner, the person they share their secrets with - then when they suddenly become single, what do you know? You are now their #1 option. BAM - shankshaw'd.
Red-Haired Shanks is a character from the popular and ongoing manga series and anime, One Piece. He plays a significant role in the life of the protagonist, Monkey D. Luffy, as he is what fuels Luffy's dream of becoming the Pirate King.
This man is the coolest character to ever grace the One Piece universe, and I need to see more of him.
Person #1: Bruh, I adore Aokiji. Coolest guy ever.
Person #2: Are you kidding? Have you even READ/WATCHED One Piece? Red-Haired Shanks world domination, my dude.
Person #1: Dude, Aokiji can literally turn to ice. He's made of ice. He can make ice. He is the physical manifestation of "cool".