The Twin Lumberjacks, A. Bumpkin and B. Bumpkin, are characters from The Legend of Zelda: A Link to the Past. They are two green-clad twins who live in a cottage situated between Death Mountain and the Lost Woods.
When Link first encounters the Twin Lumberjacks, they are attempting to cut down a tree to the southwest of their cabin. While they saw, A. Bumpkin explains to Link that a mysterious fog has recently fallen over the forest, while B. Bumpkin states that the tree feels rather odd as they cut it.
When Link returns to the site of the tree at a later time however, the lumberjacks are gone. With the twins out of his way, Link uses his Pegasus Boots, and charges into the tree, revealing a hole that he falls into, presumably the reason the tree felt odd. The hole leads to a cave with a Piece of Heart inside.
The Japanese word for "lumberjack" is pronounced "Kikori". This, combined with the overall appearance of the Twin Lumberjacks, leads some to believe that they were the inspiration for the Kokiri race in The Legend of Zelda: Ocarina of Time, or are possibly Kokiri themselves.