Why do pirates fly that skull and crossbones flag, and why is it called the Jolly Roger?

The term "Jolly Roger" is a corruption of the French phrase "joli rouge" (beautiful red) that refers to the red ensign that English privateers flew by order of the Admiralty in 1694. However when the War of Spanish Succession ended in 1714, many privateers turned to piracy and some retained the red flag. as to the skull and crossed bones motif on the pirate flag it might of served as a Memento Mori, meaning "remind yourself of your own death." or in case of the pirates to remind their victims of their own mortality and to emphasise the pirate's fearsome reputation and to cause the merchant to surrender rather than fight.

1 - The traditional "Jolly Roger" is associated with the pirates of the Atlantic seaboard and Caribbean in the late 17th and early 18th centuries. There were actually many different pirate flags at the time, only a few of which resemble the common "Skull and Crossbones" that we know today. It is believed the name "Jolly Roger" is derived from the French "Joli Rouge" which means the Red cloth. Early records indicate that the red flag was often flown by pirates as meaning "No Quarter Given."

2 - The Jolly Roger, Old Roger, or just plain Skull and Crossbones is the definitive symbol of the pyrate. Although no one knows for certain, it is believed that the name derives from joli rouge, which means "Pretty Red" in French.

3 - The flags were meant to strike mortal terror in the hearts of the pirate's intended victims. They often featured skeletons, daggers, cuttlasses, or bleeding hearts on white, red, or black fields. The skull and crossbones motif first appeared around 1700 when French pirate Emanuel Wynne hoisted his fearful ensign in the Caribbean -- embellished with an hourglass to show his prey that their time was running out.

Because the first design was a pair of ulna's parallel, with the patellae bones above and below them. The flag was called "the leagues" which had something to do with the sails and the wood of the ship.

It didn't work so a skull replaced the patellae, and they used thigh bones crossed to instill fear. As for the name "Jolly Roger"? That came from Davey Jone's grandfather.

It's not all pirates flag, just the pirate Calico Jack, who created it for his own ship. As a side note, a psychic once told me that in my past life I was Calico Jack. I don't believe in reincarnation, but I thought it was pretty cool to think maybe I used to be a world famous pirate.

some think it might have somthing to do with the knights templers and the flag might be an insult to the vatican calico jacks flag is in the film cutthroat island