Entrepreneur Elon Musk has founded companies that build electric cars and send stuff into space. But his next project might be a bit more, well, down-to-Earth.

In a string of tweets last month, Musk proposed a new tunnel digging venture called “the Boring Company." (Get it?)

“I am actually going to do this,” he wrote.

It seemed like the joke — if it was a joke — would end there. But on Wednesday morning Musk was back at it.

Asked where the tunnel would go, Musk responded that it would start “across from my desk at SpaceX,” which is in Hawthorne, Calif., south of Los Angeles. It would then follow the busy Crenshaw Boulevard and the 105 Freeway to Los Angeles International Airport, which is about 6 miles away.

Is Musk for real? It's hard to tell. “The Boring Company” is a pretty weird name, even by the tech world's low standards. (For one thing, unlike a lot of start-ups, the name still has all its vowels.) Representatives for SpaceX did not immediately respond to a request for details on the venture.

Musk did offer this, though: