Verb: description of a co-worker taunting a fellow co-worker or the boss after doing no work. Similar to Squirrel Nutkin in the "Tale of Squirrel Nutkin" by Beatrix Potter.
Usually meaning ''Double or nothing''. Usually said by nerds or geeks. Most commonly associated with a fat green blob in a gray addidas sweatshirt clinging to the ceiling of your closet. Yoshi.
Mario: Man, I did Peach a few seconds ago, should I do Daisy now?
Yoshi: Dubbo Nuttin!
Luigi: ...Mario. She's my wife.
Mario: Exactly.
Yoshi: Dubbo Nuttin!