What's the best way to mend Greece's financial problems? By playing swapsies with the US, at least according to Germany's Wolfgang Schäuble.

Recalling a recent discussion with the US Treasury Secretary, Schäuble told Bloomberg: "I offered my friend Jack Lew these days that we could take Puerto Rico into the euro zone if the U.S. were willing to take Greece into the dollar union.

"He thought that was a joke," he added.

Presumably Schäuble was joking, but it was quite a flippant gag from the Finance Minister, who has been a harsh critic of the leftist Athens government.

Equating the two nations, even in jest, is a little insensitive when their situations are completely different.

Not only do Greece and Puerto Rico have vastly different populations and GDPs, but, as Vox notes, Puerto Rico owes about $70 billion (debt-to-GDP ratio of nearly 70 percen), while Greece owes €323 billion (about 172 percent of Greek GDP).

Greece’s government has submitted its reform proposals to its European creditors in a final bid to secure bailout funding and avoid crashing out of the single currency.