A mom and her two children blew their chance to appear on today’s first-ever kid-friendly episode of “The Price Is Right” — by not cheering loud enough.

“I really liked them in the interview,” producer Stan Blits says. “They were total Americana — nicely dressed, good looking. I thought ‘Let’s give them a shot.’

“But I watched them [in the audience], and they didn’t applaud. They weren’t cheering. If you die off on me during the show, you’re out!”

Blits, who has worked on the show for 34 years, is responsible for screening every single member of the studio audience before they enter the studio.

He then hand picks who gets called to “Come on down.”

“Stan is really good at judging people right away,” host Drew Carey says. “He hardly ever makes a real mistake.”

Most people still think contestants are chosen at random, Blits tells The Post.

“I always tell people: ‘If we drew names out of a hat, we would be off the air in a month.’”

When he spots a potential winner, Blits, 56, drops a top-secret code word and his assistant adds the name to a special list.

“I jump around like a court jester out there,” he says. “I am looking for energy, sincerity and potential humor. And if they can equal my energy or exceed it and maintain it, they are at the top of the list.”

The entire “casting” process, he says, takes about two hours.

“I have people who come back over and over and over,” he says. “Our record is 158 times. That person still hasn’t made it on.”

Hopefuls can improve their chance of getting picked by following these tips, Blits says:

*Look like you’re having fun: “If you can keep the energy up and keep my attention that way, you have potential.”

*Don’t be too aggressive: “Some people think jumping up and down or waiving their fist will help. But it doesn’t.”

*Don’t try to bribe him: “People bring me stuff all the time, but I can’t take anything. Not even a business card.”

*Pretend you don’t know who he is: “People will put my face on their T-shirts, but the show can’t be about me. There can’t be an awareness that I am here.”