Jimmy Fallon: Nancy Juvonen is the Coolest Girl

Thanks to his recent engagement to producer Nancy Juvonen, Jimmy Fallon is on cloud nine.

"I'm just really excited right now and just happy. I'm the luckiest guy on earth," the 33-year old star said. "She's the coolest girl in the world."

He was among the celebrities who stopped by to pay tribute to comic legend Billy Crystal when he received this year's annual Mark Twain Prize for American Humor at Washington, D.C.'s Kennedy Center on Thursday night.

Jimmy Fallon and his bride-to-be still haven't picked a wedding date yet.

"We're still planning it," he says. But "the sooner the better for me. I'm in love."

Nancy Juvonen, 40, is Drew Barrymore's long-time business partner, and produced Fallon's terrible 2005 romantic comedy, Fever Pitch.

So was the SNL alum's proposal to Nancy Juvonen serious or funny?

"It was serious," Fallon said. "I did the one knee thing. I tried not to cry before she did. I was definitely breaking down a little bit. I don't even remember what I said."

Ironically, Jimmy Fallon plays a man who's commitment phobic in his new movie, Rockett, with Sharon Stone, Tom Arnold, and Lucy Liu, opening November 20.

In real life, he doesn't even want to miss out on the wedding planning.

"Oh, I have to be [involved]," he says. "We're trying to get a guest list together. But it's all fun stuff. She's a cool girl and it's no stress at all."

Joining Fallon at the Kennedy Center Thursday were Robin Williams, Whoopi Goldberg, Barbara Walters, Danny DeVito, Robert DeNiro, Martin Short, Rob Reiner, Jon Lovitz, sportscaster Bob Costas, and Yankees manager Joe Torre.