Viking: Someone who throws up on someone multiple times -- Usually at a party or wedding.
Basically doesn't mean this, but hey, it's Urban Dictionary, and here we type out definitions that make absolutely no sense or relation to the word itself or the reader, other than because we're odd people that like to put our strange, random personal meanings behind words.
Person 1: "Hey did you see what happened last night at the party? Jeff puked on someone.. Twice!"
Person 2: "Yeah i know. What a viking.."