Why was the pirate flag called the "Jolly Roger"?
Of course he's jolly because he hasn't any lips, but who was that flayed "Roger" immortalized by the buccaneers on their skull and crossbones? What part of the skeleton are the crossbones taken from? Is he any relation to the "Roger" who is continually being evoked by fighter pilots and other military types?
He's jolly because he hasn't got any lips? What kind of weird coastal humor is that supposed to be? Better leave the witticisms around here to me.
Jolly Roger bears no relation to Roger Wilco. The origins of the term are disputed. According to one theory, the buccaneers who operated around the West Indies in the 1600s used a red flag dipped in blood or paint, whichever could be gotten more conveniently. The French supposedly called this the "joli rouge," which the English, with their traditional disregard for the niceties of pronunciation, corrupted into Jolly Roger. Later the term was applied to the familiar black-flag-cum-bones that began to appear in various forms around 1700.
An alternative hypothesis involves certain Asian pirates whose chiefs called held the title Ali Raja, "king of sea." The English naturally thought that THEY were the kings of the sea, and appropriated the term, suitably amended, for their own use. Unfortunately, both these explanations, as one historian puts it, "are so plausible that neither can be accepted as correct," plausibility being pretty much a sure sign of error in the etymology business. Some venture the opinion that Jolly Roger may simply derive from the English word "roger," meaning a wandering vagabond, noting that "Old Roger" was a popular canting term for the devil. The bone of choice for the crossbones, I suppose, would be the femur, or thigh-bone. Dare I ask why you want to know?
Also see The Straight Dope: Did pirates bury their treasure? Did pirates really make maps where "X marks the spot? and Why are pirates depicted with a parrot on their shoulder? What's the origin of the skull and crossbones pirate flag?