Why Treasury Secretary has been practicing her signature

Catch up quick: Arguably one of the coolest parts of serving as the treasury secretary is your signature on all U.S. banknotes. But Yellen's hasn't appeared yet, for a bureaucratic reason.

• New money can't be issued until the country has a treasurer, whose name also appears on the dollar. The appointment of the current treasurer, Marilynn "Lynn" Malerba, didn't happen until June. She was officially sworn in this fall.

The intrigue: Yellen said her predecessors made at least one mistake she won't repeat: Signatures of former Treasury Secretaries Jack Lew and Timothy Geithner were so illegible that they became a punchline.

• What they're saying: "I knew that this was something that you could screw up, and I wanted to get it right. I practiced and I practiced," Yellen told Colbert.