One commentator tried to explain this in terms of Brazilian sporting culture. Remember many of the local people turning up to watch have no knowledge of the sport involved - that indeed is an important aspect of the modern olympics; the spreading of sports around the world.. So they don't know that it is not the done thing to take photos when the golfer is getting ready to tee off, and they don't know you are supposed to be quiet when a tennis player is getting ready to serve. Brazilians, it seems, think that when they have paid their money to be spectators, they are not supposed to be passive. They are supposed to pick their favourite team or player and actively support them (by cheering) and disadvantage their opponents (by booing). And it doesn't have to involve Brazilian teams or players. Baizilians will chose Sri Lanka over Egypt if they feel like it and cheers/boo with almost the same enthusiasm as with home games. It is the same in Britain when soccer is involved - your team is cheered and the opposing team is booed and whistled, and an opposing individual player will be booed when they take a penalty. That, apparently, is perfectly fine. But the British don't like it if it is applied to other sports. The rest of the world may not share our nice distinctions. And, let's face it, those Brazilians just ain't British!
