Elon Musk, the man behind electric carmaker Tesla, SpaceX and the Hyperloop vacuum tube, has a new passion: tunnels.
"Traffic is driving me nuts," he tweeted on Sunday morning (NZ time).
"Am going to build a tunnel boring machine and just start digging."
Though it might sound like the musings of a bored billionaire, he later clarified he was serious.
"I am actually going to do this," he wrote, saying he'd call it "The Boring Company".
Mr Musk has been known to joke around on Twitter - there's even a parody account (@boredelonmusk) which tweets ridiculous tech ideas that sound like they could have come from the South African entrepreneur.
But this time he seems serious, even updating his Twitter bio to include "Tunnels (yes, tunnels)".
Then again, he once tweeted how many hamsters a new factory he was building would hold; and when one of his rockets crash-landed, took to the social network to call it an "RUD - Rapid Unscheduled Disassembly".
He even once tweeted SpaceX's technology "sucks" because it can't get people to Mars yet.
Auckland's Waterview Connection tunnel under Mt Albert cost about $1.6 billion and has taken years to build.