Many foreign visitors to South Africa have bought their own vuvuzelas to take along to matches, fan parks, and actually any place where football is being watched. An interesting thing that we noticed is that sometimes newbie vuvuzela-blowers don't know when it's appropriate to blow the instrument. Sometimes you'll find that the people not accustomed to the vuvuzela blow it when the opposing team scores a goal, or one of their star players is yellow-carded. It seemed as though these folk correlate the "paaaaaaarp" sound with a "booooooooo" when in fact the vuvuzela is intended to be blown when your team scores a goal, or plays particularly well. It's meant as a sound of encouragement.
Seasoned vuvuzela players play in rhythm with each other, producing different notes with rhythmic calls and call-backs. Kerry-Anne noticed that many people new to the instrument overwhelmingly blow single lonesome blasts that do in fact often sound like the noise that a depressed elephant would make. If you're one of these people, don't take this as negative criticism - I too class myself as a newbie and a learner vuvuzela-blower (although I do try to avoid playing the depressed elephant song). :)