Jolly Roger

The Jolly Roger is the traditional flag of European and American pirates, envisioned today as a skull over crossed thigh bones on a black field. Various versions of the Jolly Roger existed over the course of the centuries, Calico Jack'c Jolly Roger replaced the thigh bones with swords (Cutlasses).

Oda himself provided some info on the Jolly Roger, including three possible thoerized origins that have come to be accepted by experts:


 * Some say it comes from the French term "Jolie Rogue" or "red Lovely" possibly referring to blood.
 * "Roger" may have come from the word "Rogue" meaning thief or villian.
 * It may have come from the term "Old Roger" a old fashioned name for the Devil.

The Jolly Roger is hughely reconigsed to mean "danger" worldwide. The skull and crossbones themselves are commonly used on to warn people about dangerous substances or places on signs and bottles.

One Piece
In One Piece, there are many Jolly Roger flags. However, raising the Jolly Roger is considered a huge crime by the Marines, and anyone seen doing so (may it be fun or for real) will be considered criminals.