Why Label yourself?

After watching some of the "Peaceful" protests that are taking place amongst the G20 crowd I have to ponder to myself and ask the question about why groups of peaceful  protesters would want to negatively label themselves in public. How do they do so? I'm not talking about the reckless immaturity of burning a police car (that speaks for itself) but rather literally putting symbols upon oneself.  I saw many individuals wrapping themselves in flags such as the one shown here in the picture.

What is a Flag? Flags are created to represent nations with symbolism and history. The flag is able to be a pedestal for a group of people to respect and follow and feel as one. Therefore so when an individual places a Marijuana leaf rather than the Maple Leaf onto a Canadian flag, wraps himself in the flag and parades down the streets he is saying without words "Hey world! Look at me! The most important thing in my life is a hazardous health hobby!"  Individuals who place a drug as the most important thing that they could or would want to symbolize at a group protest against a meeting of the World superpowers where serious decisions are taking place is a bit of a scary thought. In our future will government be comprised of individuals who have petty individual beliefs rather than an actual desire to create the best country for his citizens?

Honestly, you're protests would be listened to much more if you showed up with a serious face and wanted to discuss relevant issues rather than parading about with groups of people that the world will label as single minded and short minded.