Elon Musk is up to something.

The Tesla Motors chief today tweeted that his company would unveil a "major new product line" at its Hawthorne Design Studio on Thursday night. The only clue? It's "not a car," he wrote.

The last time Musk sent a cryptic tweet in advance of a product launch (which promised a glimpse at his "D"), Tesla revealed an all-wheel-drive version of its Model S, the P85D.

More recently, the company rolled out a software update intended to calm "range anxiety," and threw cold water on reports that it would release a self-driving car this summer.

So what does Tesla have up it sleeve this week? Some on Twitter pointed to a February earnings call in which Musk promised to launch the "Tesla home battery" for consumers "fairly soon."

"We have the design done, and it should start going into production [in] probably about six months or so," Musk said at the time, before promising a product unveiling "in the next month or two."

As Bloomberg noted then, the move could not only allow for easier Tesla car charging, it might also let homeowners ditch their local utility.

We'll have to wait until 8 p.m. PT on Thursday for more details, but until then, those on Twitter have a few suggestions for what Musk should reveal.

Hoverboards #TeslaNewProductGuesses

— Anthony Quintano (@AnthonyQuintano) March 30, 2015

Musk, a new fragrance from Tesla #TeslaNewProductGuesses

— Alex Fitzpatrick (@AlexJamesFitz) March 30, 2015

I hope the new Tesla product is that cloning machine in The Prestige

— Matthew C. Klein (@M_C_Klein) March 30, 2015

Space elevator? Tachyon beam? Flux capacitor? #TeslaNewProductGuesses

— Alex Rubalcava (@AlexRubalcava) March 30, 2015

Wouldn't it be funny if Tesla started making smart watches?

— Scott McDaniel (@mcdev) March 30, 2015

Meerkat for your car dashboard #TeslaNewProductGuesses

— Hosam Hassan (@Objective_Neo) March 30, 2015

Tesla TX: A special collection for Target

— Matt Weinberger (@M_Wein) March 30, 2015