Supporters say it's an inspiring cacophony, but critics say it sounds like a swarm of bees, drowning out fans, commentators, national anthems and generally ruining the World Cup experience for everyone.
FIFA, the soccer-governing body in charge of the World Cup, is under pressure to ban the noise-maker. It said in a statement that for now it will only outlaw vuvuzelas if they become a physical hazard, such as if fans throw the horns on the field, but that it "continues to evaluate the use of vuvuzelas on an on-going basis."
FIFA president Sepp Blatter further clarified the body's position with a Twitter post saying, "To answer all your messages re the Vuvuzelas. I have always said that Africa has a different rhythm, a different sound....I don't see banning the music traditions of fans in their own country. Would you want to see a ban on the fan traditions in your country?"
In response to the criticism, South Africa's Johannesburg Star newspaper reports that Masincedane Sport, the company who owns the vuvuzela trademark, plans to offer a quieter version of the horn.
"We have modified the mouthpiece, there is now a new vuvuzela which will blow noise that is 20 decibels less than the old one," Neil van Schalkwyk, a partner at Masincedane Sport, told The Star. "We hope to sell these at park and ride areas and public viewing areas."
Studies have shown that the vuvuzela's noise is 127 decibels, louder than a drum or a referee's whistle.
Earplug sales in South Africa are reportedly high as fans become increasingly concerned for their hearing, and players and coaches have formally complained to FIFA about the horn. France's captain blamed the vuvuzela for keeping the players from hearing each other on the field.
Twitter is abuzz with tweets against the vuvuzela from fans in the stadiums and those watching at home. Facebook and other blogs have started campaigns to get the horn banned from stadiums.
But vuvuzela supporters are just as emphatic that it's a very South African way of paying homage to the game. For South Africans, vuvuzelas are to soccer what hot dogs are to baseball. No game is complete without them. And they have countered with their own on-line campaigns. There's now even a Twitter hashtag, #SavetheVuvuzela.
Supporters with iPhones can download vuvuzela applications. The iVuvuzela app allows users to play a short vuvuzela drone by touching a button, and a Vuvuzela World Cup app that actually allows the user to blow into the iPhone microphone to make the noise.
"Going into a stadium without a vuvuzela is like going to war and being unarmed," Petey Mthethwa, a worker from Lumoss Mouldings, a vuvuzela manufacturing company in Johannesburg told ABC News.
While the exact origins of this stadium blower are disputed, legend has it that the plastic horn harkens back to a time when South African warriors blew antelope horns to call villagers to meetings, to announce their arrival at battles or to strike fear in the hearts of their opponents.