Jonna Mendez was a globe-trotting spy for nearly three decades, briefing the president, slipping across borders armed with false identities, using cameras so tiny they fit into a lipstick tube or a blazer button.

As the CIA's chief of disguise, she helped fellow agents avoid detection. She married Tony Mendez, a fellow agent recently portrayed by actor Ben Affleck in the Oscar-winning espionage film "Argo."

In retirement, Jonna Mendez's undercover operations haven't stopped. But her priority is no longer national security.

Her new goal? To help parents find the best presents for their children without tipping their hand.

Mendez, 68, is Target's so-called Kids' Gift Detective, hired as an outside consultant during the holiday season. She's part of a scattered cadre of gift experts aiding consumers and companies in a competitive Christmas.

Sales over the Black Friday weekend were lukewarm this year, as shoppers who have adapted to tighter budgets consolidated their store visits and headed for deeply discounted items. With only a day left before gifts are exchanged, retailers are doing everything in their power to make last-minute shopping simple for their patrons.

As of Dec. 8, some 64% of consumers had half or more of their holiday shopping remaining, according to a report from American Express.

To help out, daily deals site Groupon employs a team of eight so-called Grouponcierges who point out gift trends and money-saving tips to customers, usually through social media.

There's also a small industry of independent gift consultants, such as Julie Kenney, who writes a popular blog called the Gifting Experts. Clients contact her through her Bay Area blog.

"More people want different, unique gifts instead of the last-minute things you get running to the mall," Kenney said. "There are just so many options now, it's hard to navigate."

But the only gift-advising expert with a spy's eye is Mendez.

Her tips, compiled on Target's website, coach parents to ask their children to write out their wish lists in a secret letter to Santa using makeshift invisible ink created with lemon juice or milk. The script becomes legible later when heated.

She preaches misdirection: Label packages with another family member's name or disguise them with a shipping label so children don't become suspicious. Camouflage presents inside other wrapped gifts so kids can't guess the contents from the size or shape of the box. Hide items inside the cleaning cabinet or other areas no child would think to check.

"Moms and dads have this annual problem at Christmas: How do you find out what a kid wants when sometimes they don't even know? How do you go on a covert mission to purchase it? How do you store it until Christmas?" she said. "There's an espionage equivalent in each of those steps."

She's had a lot of practice with her son Jesse, 21, who has always been difficult to shop for, she said.

When his friends came over with toys for play dates, Mendez would make a note of which playthings most attracted Jesse's attention. She'd interrogate people she calls "access agents" — coaches, teachers, carpool drivers and baby sitters who spent a lot of time with her son. She'd ask Jesse to flip through gift catalogs, watching his face "to see when he would light up."

"Today, you might call it biometrics, but it's body language basically," she said. "When kids like something, they talk faster, their eyes light up, they sit up straighter."

Mendez said her skills are now "second nature."

But in 1966, as a 21-year-old in love with Germany, all of her focus was on staying in Europe. With no grasp of the language and no work permit, Mendez said she talked herself into a secretarial position at a Chase Manhattan Bank outpost.

From there, she was recruited by the CIA, which eventually brought her to Washington to work a similar job. When she indicated that she might leave to work at the Smithsonian, the CIA persuaded her to stay by offering her more exciting work in the field.