The annoying horn that plays during FIFA World Cup Matches is called a "Vuvuzela"

The exact origins of the vuvuzela are disputed, but they have been seen in South African football matches since at least the 1990s. It's become part of the South African football experience. The instrument is supposed to resemble the sound of an elephant, but thousands of them in a stadium make a sound reminiscent of a swarm of bees.
The origin of the name itself, "vuvuzela", is also uncertain. It might mean "making noise" or possibly a variation on the word "shower" because it looks like a shower head.

Listening to vuvuzelas for an extended period of time puts you at risk for hearing loss. You can lose hearing from listening to sounds at 100 decibels for only 15 minutes. The vuvuzela's sound is the equivalent of 127 decibels.