Now, the 25-year-old Blue Springs, Mo. native is a household name -- the latest winner of "American Idol" -- and has fans going crazy.
They sure did on The Early Show plaza, when Cook visited New York for the first time. The young ladies were swooning and screaming.
"This is ridiculous. Wow!" Cook told co-anchor Maggie Rodriguez.
And Cook kidded that, if he's ever had that effect on women before, "They never told me before this show. So I'm going to go with it now!"
Have any girls who broke his heart called and asked him to take them back?
"No, actually. I'm sure they still thought they made the right decision. I'm just a nerd who got lucky!"
Rodriguez was quick to disagree.
Cook said he had to be persuaded to even try out for "Idol."
He showed up with his brother, who did want a spot in the competition.
But, "It actually took a producer from the show," he recalled for Rodriguez, "shoving a camera in my face, asking me why I'm the next 'American Idol.' I was like, 'I'm not. I'm not auditioning.' He goes, 'Well, you are now!' And I turned to my brother, and he was kinda looking at me like, 'See, you should probably try it.' And I was like, 'Well, what do I have to lose?' "
The rest, as they say, is history.
And the night Cook made history, he says, he fully expected the other David, teen crooner David Archuleta, to take the crown.
When "Idol" host Ryan Seacrest was announcing the results of the fan voting, he said the winner is -- then paused. And Cook says he absolutely figured the next word out of Seacrest's mouth would be Archuleta.
"I was there Tuesday," he said to Rodriguez. "I heard what the judges said."
They praised Archuleta highly.
"We showed up Wednesday morning to do dress rehearsals for the finale," Cook continued. "Nigel (Lythgoe, the show's producer) came up to us and said, 'Davids, the votes are in. There's over 97-and-a-half million votes, and one of you got 56 percent and one of you got 44 percent. As soon as he said that, I said (to myself), 'OK. It's "Archie." I can wear silver very well. It's a monochromatic color. It goes with black. It's perfect.' "
Of course, it turned out, it was Archuleta who would be fitted for the silver of a second-place finisher.