A series of 3-page long One Piece omake manga strips drawn by Eiichiro Oda. Their stories tend to parody other genres such as science fiction or fairy tales. Most of them were initially published as bonus content in One Piece Complete Collection between the 2nd Log (2005) and the 20th Log (2012). The anime adapted the five initial chapters in the recap episodes 279–283.
The Straw Hat Theater concept was created when Oda was given three blank sheets of paper by his editor and told to draw anything.
(Source: One Piece Wiki)