Much as I hate the way Google listens in on everything I do, I decided to use the kids tablet to give it a whirl. Here is what the first half dozen relevant hits gave me.
UrbanSlangDictionary - Slang name for a GT2860R (GT28RS) Turbo. Usually used in conjunction with a Nissan SR20DET powerplant.
FullRace.com - The GT2860RS is one of Garrett's most legendary GT ball-bearing turbos. Nicknamed the 'Disco Potato' after the car that first used it—a B15 Nissan Sentra with a wild paint job—this turbo has become a staple in the tuner world and for good reason. It's a reliable platform that delivers good power.
Miata Forum - Disco" comes from the car's crazy orange metallic paint, and "potato" comes from the affectionate nickname given to the B15 Sentra by those who likened the car's round silhouette to the Irish food staple.
VWVortex - It refers to the nick name of the guy who originated the turbo specs for use on his nissan years back, and it got popular with Garrett and they just dubbed it that.
Patrol 4x4 - It was developed by Garrett in the US for a project car called the Disco Potato with an SR20 powerplant.The car's power was impressive, 280 hp at the wheels, but not earth-shattering. The driving experience however, was. Throttle response was excellent, turbo lag virtually non-existent, and the tyre-smoking horsepower was outstanding. The turbo spooled up early, making so much torque, that the best quarter-mile time (13.7 at 104.5 mph) was achieved launching in second gear. The vehicle was so successful that Garrett named the turbo as the GT28RS.
GTR.Co.Uk - "Disco Potato" Came from a car that they used to help develop the Turbo with, It was a Nissan Sentra SE-R that had a color shifting paint that looked sorta brown (like a potato) and sifted to green and purple (like a disco i guess??). It got alot of media coverage in the states, and competed in the sport compact car Ultimate Street Car Challenge". The compressor efficiency map looks like a potatoe as well.
OK, I've had enough of Google.
I didn't select or pick Google hits. I just took the first relevant ones google suggested. They might not be what you would find because google knows us and presents info based on that knowledge. That's one of the reasons I don't like Google. I chose the kids tablet because they have no car history and because I don't want to use Google on my own devices.Basically though, nothing Google found suggested that it's an official name, it's all just street slang with a meaning that varies as widely as where it is used.
The common thread is the car colour, the car shape, the turbo itself, and the guy who first used it. I think it's fair to say that any one of these attributes without the others isn't a disco potatoe! LOL!