Does the U.S. need a trillion-dollar coin?

There's an idea floating around that is undoubtedly crazy. But it has gained traction and support from some of the biggest economic thinkers in the U.S. As another showdown over the debt ceiling looms, experts say the whole thing could be put to rest by simply minting a $1 trillion US coin.

Yes, a trillion-dollar coin. It's been endorsed by Nobel Prize laureate Paul Krugman and debated by Treasury Secretary Janet Yellen, though she didn't give the idea a ringing endorsement.

"I'm opposed to it, and I don't believe we should consider it seriously," she said in interview with CNBC. "It's really a gimmick, and what's necessary is for Congress to show the world can count on America paying its debts."

The $1 trillion coin idea is indeed a gimmick. But it's also perfectly legal. The man credited with coming up with the idea says it's a loophole to get around an equally absurd idea: the U.S. debt ceiling.

"On the one hand I think it's funny," said Atlanta based lawyer Carlos Mucha. "But on the other, honestly it's sad that what's standing between us and the government having an economic crisis is this gimmick."

So, how did we get here? It starts with the debt ceiling.

Remember, The U.S. Congress passes bills, those bills become laws and policies. But there's a catch. Congress also has to give permission to the federal government if it wants to take on more debt to pay for these projects.