In Dutch we call it a "geuzennaam", after the Geuzen, who once upon a time battled for Dutch independence from Spain, and had adopted their name from what they were originally disparagingly called by the powers that be (gueux = beggars)...
Since this thread is so pointless to begin with . . . The Spanish "owned" the Netherlands (roughly, modern Holland, Belgium, Luxemburg, and parts of northern France and western Germany) because the Duke of Burgundy married the widow of the Count of Holland, who had been the highest ranking aristocrat in the region--the rest of the territory belonged to the Dukes of Burgundy as of right. The Spanish got into the act when Philip the Handsome married Joanna the Mad (daughter of Ferdinand and Isabella), and Philip therefore inherited the Burgundian possessions--including Holland--as well as the Spanish throne. Their son Carlos became the Holy Roman Emperor Charles V, who was the opponent of Martin Luther.
The Duke of Burgundy, Philip III had established an order of chivalry which he named the Order of the Golden Fleece--a reference to Jason and the Argonauts in Greek mythology. Therefore, his male descendants were each the head of the order as they succeeded to their respective estates. Membership in the order was considered a great prize and honor by members of European aristocracy.
In 1555, Charles V abdicated in favor of his son, Philip II. However, although Philip was the King of Spain, and controlled the largest empire in the world, the German electors, despite all promises of bribes, weren't stupid enough to repeat the mistake they had made in electing his father Carlos. In honor of the ascension of Philip to the throne, the "Spanish" (read, Belgians and Dutch) got up a little war with France, and the most dramatic action took place at St. Quentin in Picardy. The Count of Egmont and William, Count of Nassau, had distinguished themselves in that little war.
The French were as civilized as anyone else in those times, so, having lost the silly little war, they invited the "Spaniards" to come to Paris for a big party. At that party, the Count of Nassau, William, was honored especially, and King Henri II of France confirmed him in the possession (by virtue of his mother) of the Principality of Orange in central France--making William, Count of Nassau, the first William of Orange. Henri then invited William to go hunting with him, and talked about the plans he and Philip were getting together to slaughter a bunch of Protestants. William was smart enough to keep his mouth shut, and even though nominally a Catholic, he warned the Protestant nobility of the Netherlands of the plan. Because kept his mouth shut at the right time, the French named him Guillaume le Taciturne--William the Silent.
There had been an understanding (or at least the aristocracy of the Netherlands thought there had been) that the Inquisition would not be imported into the low countries. But the Spanish grandees sent to the Netherlands threatened the Protestant iconoclasts with the inquisition, and people like Egmont and Count von Hoorn began a movement of open opposition to the impositions of the Spanish.
In mockery of the Order of the Golden Fleece, of which Philip was the head, they created for themselves rich and expensive necklaces such as those worn by the member's of the Order, but where a golden fleece was suspended from necklaces of members of the Order, the Dutchmen and Belgians had the traditional symbols of beggars--the begging bowl, the crutch and a tall felt hat. This was because the Spanish grandees had sneered at them as "beggars," so they wore the title like a badge--literally. That really, really pissed off the Spanish, who were rather humorless at the best of times.
And that was how the Dutch rebels became known as beggars. In particular, they were called the Sea Beggars, where they routinely made monkeys of the Spanish.