Bernie Sanders and Donald Trump said they want to debate each other. Yes, really.

Hillary Clinton says she has no interest in debating Bernie Sanders before California’s Democratic Primary. But if she won’t, Donald Trump will.

On ABC’s Jimmy Kimmel Live! on Wednesday night, Kimmel asked Trump if he’d be willing to debate Sanders instead, with the proceeds going to charity. Trump said he would. And Sanders tweeted a few minutes later that he’s in.

After Clinton initially turned down an invitation to debate Sanders on Fox News, the network considered hosting a Sanders-Trump debate in February, the New York Times’ Nick Corasaniti reported in March. But Trump pulled out at the last minute, citing “scheduling conflicts.”

If the debate actually happens this time around — and if it’s going to, Sanders and Trump need to find a network to host it — it would be unprecedented. The Democratic National Committee and the Republican National Committee both frown on networks inviting candidates to debates that the committees didn’t approve.

But the committees mostly enforce those rules by threatening networks’ access to and candidates’ participation in future primary debates. Since Trump has the nomination locked down and the California primary is almost the last of the 2016 cycle, if Sanders and Trump want to debate and a network will host it, their parties might not be able to stop them.

Trump, being Trump, is now suggesting that it might just all have been a joke:

But embracing the idea and backtracking on it are both emblematic of Trump’s campaign.

Donald Trump was a successful television personality because he understands what makes great television. (Even if that meant embracing disturbing ideas, like The Apprentice: Race War.)

And a Sanders-Trump debate certainly could be wildly entertaining: two unconventional, older New Yorkers, neither of whom can pronounce “huge” correctly, defending their very different beliefs.

It’s less clear why Sanders — who would need to win California in a historic landslide to capture the nomination — would go along with this. Sanders insists he could still win, but if he really believed he was going to, there’s an easy response to Trump’s challenge: that he looks forward to debating Trump on September 26, when the first general election debate is scheduled.

There could, imaginably, be some value in watching Sanders and Trump, or any two candidates from opposing parties, face off. Sanders can attack Trump on issues Republicans have hesitated to engage with for fear of alienating their base: his racist remarks and proposed policies, his business record, his wealth. Equally, Democratic voters would get a chance to see how Sanders responds to much more savage attacks on his proposed tax increases and his identification as a democratic socialist.

In general, debates between candidates of opposing parties while the primary process is still going on might not be a terrible idea. Voters might want to know where their prospective candidates are vulnerable to general election attacks from the other party, or how they might moderate their positions if they’re criticized.

But that information is only useful if voters still have options to choose from. And when both parties essentially have their nominees, it’s awfully late to schedule an inter-party debate. So we’re left with this: It could be awfully entertaining. Two comedians, James Adomian and Anthony Atamanuik, have been embracing the idea with a very funny “Trump versus Bernie” debate tour for months.