Dazzling Demi Moore got a “dude” awakening when she showed up to do David Letterman’s show — a flock of young guys shouted their willingness to replace her 25-year-old boyfriend Ashton Kutcher.

As she entered the Manhattan theater where the “Late Show” is taped, a herd of male admirers in heat turned on their “charm.”

One guy bellowed at the 40-year-old beauty that he was 27 — and asked if that was too old for her.

Another horn dog howled, “I can satisfy you better than Ashton, I’m only 23.”

Every bit the lady, Demi ignored her rude suitors outside the June 23 taping.

“Demi didn’t even look at the guys,” revealed an observer. “She just jumped out of a black SUV and practically ran into the studio, bypassing a crowd of about 30 people with magazines and photos for her to sign.”

Once safely inside, Demi had to deal with Dave’s questions about her relationship with the hunky star of “That ’70s Show.”

When the bedeviled “Charlie’s Angels” star left the studio an hour later, her frenzied “fan club” was still waiting — and had more to say.

“I’m young and strapping, too,” one of them yelled to her. But Demi didn’t answer. She was back in the car in a split second — a blur of black hair.

Earlier in the week, Demi took a big bite out of the Big Apple with Ashton, partying at top clubs. They also caught a Norah Jones concert — and (sorry, guys) the pair seemed in perfect harmony.