Tesla owners can now change the car's horn to sound like anything they want, from clips of songs to farting to bleating goats

• Tesla's new Boombox mode came in late December as part of a holiday firmware update.
• The feature lets drivers change the sound their car makes when driving, swap out the horn, or broadcast music from the car's media player.
• Since Tesla released the feature, numerous videos have appeared online of Tesla owners playing around with preset sound effects — like a fart, bleating goat, and an old-style horn — and loading in custom audio.
• Tesla is known for including playful features in its cars — like a virtual whoopee cushion — that may not serve any practical purpose, but foster brand loyalty and word-of-mouth marketing.

As the world's best selling electric cars, Teslas don't draw as much attention as they used to. But owners are now turning heads thanks to a holiday software update that lets them broadcast music, fart noises, or custom audio outside the car.

The new Boombox mode arrived as part of a late-December firmware update that also added new games and other features. Tesla fans have been waiting for the feature since CEO Elon Musk said in August that the cars would soon be able to "play snake jazz or Polynesian elevator music through its outside speakers wherever you go."

Although Tesla's Easter-egg features don't add any value from a driving perspective, they may help foster brand loyalty and excite the carmaker's fanbase, as evidenced by the numerous clips that have surfaced online of Tesla owners testing out the new sounds and filming the reactions of unsuspecting passersby.

The videos are also great word-of-mouth marketing for a company that has no advertising budget or public relations department.

Read more: 10 times Elon Musk proved Tesla doesn't need advertising

Boombox lets drivers swap out the standard horn sound for one of ten preset sounds like a fart, bleating goat, "La Cucaracha," or applause. They can also upload up to five custom audio clips. But you can only replace the normal horn when parked, according to Car and Driver.

—TESLA_saves_lives (@SavedTesla) December 31, 2020

@djstabio

Part 2 of Tesla custom horns! ##foryou ##tesla ##fyp

♬ original sound - Lucas Stabio

The noisy feature lets drivers use their Tesla as a boombox - as the name implies - to broadcast any music they'd like, but only when the car is parked. Ludacris' "Move B----" was a clear choice for some owners.

—Tesla Owners Online (@Model3Owners) December 29, 2020

Owners can also change the sound their Tesla makes while driving or while it navigates itself out of a parking spot using the driverless Summon mode. Some of the presets available include Polynesian elevator music, rainforest, and a soundtrack that resembles an ice cream truck.

—Dave VanderWerp (@DrivenItAll) December 26, 2020

Boombox is only available on newer Model S, Model 3, Model X, and Model Y cars with built-in external speakers, which the National Highway Traffic Safety Administration mandated on quiet electric vehicles for pedestrian safety starting in September 2019.

"Snake jazz" - a hiss-based genre that's a reference to the cartoon "Rick & Morty" - probably wasn't what the NHTSA had in mind when it required electric cars to make some noise at low speeds, but Tesla tells drivers to "Please check local laws before use in public spaces."