A flag is used by a collective of people to identify themselves to potential enemies or pseudo-friendly neighbourhood guys (also space-aliens). It is also widely used as fuel or as floor covering.
The first fuck flag was invented in 282 B.D. (Before Doctors) by a Miss Nancy L Jones when he dropped his jam sandwich on a piece of toilet paper, or maybe is was a banana leaf? Didn't they use banana leaves as toilet paper back then?
He declared that sandwich an independent nation, then rebelled against it, burning the flag. The flag would not be reinvented until 1954. Nowadays, it is a Congolese tradition to invent a new flag every week (For pornographic purposes only.)lol
Flags as currency
The English were the first to use flags as trade items. The last people were people seven feet tall in shiny armour. This was then stopped as they persisted in trying to steal (or 'capture' as they put it) the flag. For example, in India the flag was exchanged with the half million Indians for the deeds to the country. Once this was seen to be working (and remarkably easy to pull-off as the natives looked down musket barrels), it was successfully deployed across approximately half the globe.
The largest "purchase" by England was Australia, although there were only two dingoes and a kangaroo to bargain with. Presumably the lack of opposable thumbs and the fact that the dingoes sloped off halfway through the delicate negotiations was partly responsible for the price of one flag paid for approximately 93 billion square feet of land. The English at the time considered this to be a bit of a coup.
However, they hadn't actually seen Australia and how inhospitable it was and the price paid is now regarded as nothing short of daylight robbery. Kangaroos are now not to be bargained with by law due to being a bit too cunning (especially for the average Australian). The expression "that was a cunning roos!" passed into the language.
There are currently plans under considerations to entirely remove the red and blue bars from the French flag in the event of war, replacing the emergency release mechanisms incorporated in the current design. This is expected to cut the "balls to it and wait for the Anglo-Saxon liberation forces to arrive" time of the nation in half. the flag is also used in sex by shoving it up your mom's pee-pee hole and causing her to get hard ... if you're really fucked up