1. A verb meaning to take something by force or bully someone into giving you something that rightfully isn't yours. Also could mean using brute force to get your way either with people or inanimate objects such as vending machines or engines i.e. banging on it until it gives up the damn Snickers bar/works. Basically any acttion involving intimidation or force/violence that gains material possessions such as food, cars, women, grapefruits, mufflers, candy, Copenhagen, towns, flying carpets, ninja swords, herpes. Derived from how the Norse and Danish viking generally wrecked people's shit to get stuff they wanted.
2. The word could also be used to describe an action of destruction that deprives anyone from enjoying something, based on the mentality of "If I can't have it, then no one can."
Exp. of use #1: Dude, I was so hungry, I had to viking this candy bar from that nerd.
Exp. of use#2: I know all you guys liked her, but I hate you assholes and that's why I vikinged the shit out of Misty last night. Good luck with that.