WASHINGTON -- Sen. Elizabeth Warren has gotten an awful lot of mileage out of her popular appearances on "The Daily Show With Jon Stewart." But it was something of a revolting experience the first time she prepared to sit across from the sometimes caustic comedian.

She had such a bad case of nerves before the 2009 broadcast that Warren threw up. Twice.

"I was miserable. I had stage fright -- gut-wrenching, stomach-turning, bile-filled stage fright. And I was stuck in a gloomy little bathroom, about to go on The Daily Show," the Massachusetts Democrat recalls in her new book, A Fighting Chance, due out next week.

"I was having serious doubts about going through with this. I had talked to reporters and been interviewed plenty of times, but this was different. At any second, the whole interview could turn into a giant joke -- and what if the joke turned on the work I was trying to do?"

"For the zillionth time, I asked myself why on God's green earth I had agreed to sit down with Jon Stewart," Warren writes.

The interview got off to a rough start, she recounts, when "he immediately began hurling baseballs straight at my forehead. The beginning was a disaster."

It grew worse when Stewart mispronounced the acronym for the Public-Private Investment Program, or PPIP -- pronounced "pee-pip."

She corrected him and instantly regretted it. When Stewart asked her what it stood for, she froze and had to admit, "I forget."

Still, he kept her in the chair until after the commercial break, when he gave her a chance to explain why the country needed to step up regulation of the imploding financial industry.

Then Stewart was impressed.

"[This] is probably the first time in probably six months to a year that I feel better," he told her. "I don't know what it is you just did right there. But for a second that was like financial chicken soup for me."

Little did he know, Warren was probably the one who needed it.

Watch part 1 of the "Daily Show" episode: