Inside the Amazon Box—Your Swiffer Refill or Your Christmas Gift?

Ms. Juane spent a night mulling it over before telling her parents what she’d seen. “I didn’t want them to be disappointed if I couldn’t be, like, ‘Oh, my gosh!’” says Ms. Juane, a day-care worker in Dallas.

This holiday season has seen a boom in online shopping. Yet with so many families buying gifts through shared accounts, digital indiscretions are wreaking havoc on many Christmas surprises. At the same time, millions of Americans receiving gifts shipped from loved ones are finding the parade of identical cardboard boxes can be hard to distinguish from their own purchases—with many mistakenly opening their presents long before Christmas morning.

When a package arrived on Aimee Truchan’s doorstep in San Diego earlier this month, she did what she always does and casually slit it open.

“I’m thinking, ‘Oh, good, the Swiffer refills for my mop are here,’” she says. Inside, though, was a whiskey ice cube tray: her gift from her niece’s husband, part of her family’s annual Secret Santa, their main gift exchange. It was an anticlimactic experience, says Ms. Truchan, a marketing executive in her 40s.

In Bakersfield, Calif., Lexis Hanssen, 25, first learned about her sister’s Christmas gift after spying an unfamiliar $15.61 Amazon charge on her credit card. Ms. Hanssen, an accountant, worried she might be the victim of fraud.

Amazon customer service told her the charge was for a Disney cookbook. It turned out Ms. Hanssen’s sister had mistakenly clicked on her card when using their shared family Amazon account to buy her a present.

“Merry Christmas,” her sister texted, after being alerted to her gaffe. “The Christmas present[s] you pay for…are the best ones, right?”

Many shipping presents this year in lieu of in-person gatherings are asking others in the recipient’s household to nab incoming packages and do the wrapping. But Timothy Prine, 35, a system administrator in Scottsdale, Ariz., said he and his wife didn’t feel comfortable making such requests.

“We didn’t want to be like, ‘Hey, here’s more presents for you to wrap,’” says Mr. Prine, who opted to pay for gift wrapping from online vendors instead.

This Christmas, he and his wife received around 18 gifts that had been ordered online and shipped directly to their home. Mr. Prine says they accidentally opened around five or six, but dutifully wrapped the presents anyway and placed them under their tree. “That way we could send photos to the family,” he explains.

Others have also decided to keep up the ruse. In West Hartford, Conn., Grace Chisholm’s boyfriend purchased her a Christmas present on their shared Amazon account, but accidentally wiped out her gift card balance in the process.

“It was awkward,” says Ms. Chisholm, who noticed the purchase only after trying to figure out why her gift card balance had suddenly been emptied. Ms. Chisholm, 24, a healthcare administrator, alerted her boyfriend. He paid her back.

Still, she didn’t have the heart to tell him she’d seen her gift—a ridged cast-iron pan—in their order history. When the two exchanged gifts, Ms. Chisholm did her best to feign astonished delight: “I’ve nailed my ‘receiving gifts’ face, I’m very good at acting surprised.”

With more people home all the time, keeping surprises intact has been especially hard this year, says Nickie Fletcher of Mobile, Ala. A gift she’d purchased for her husband—a woodworking tool—arrived in a box with the brand’s distinctive red-and-white logo plastered all over the packing tape.

“It would’ve been an immediate giveaway,” says Ms. Fletcher, 37, who managed to get to the door before her husband did. On other occasions, the family’s Alexa device alerted them to the contents of Amazon packages they were receiving, both of which contained gifts. Only Ms. Fletcher’s husband, who had ordered them, was in earshot.

Eric Van Gogh, a Brentwood, Calif.-based YouTube video maker and aspiring actor, said he stopped purchasing gifts online this year after multiple mishaps. In one case, he’d opened a large box addressed to him, thinking it was some lighting equipment he’d ordered. Instead, he found a gaming chair. “I was super confused,” says Mr. Van Gogh, 24.

He told his long-distance girlfriend in Orlando, Fla. about it, thinking it was a funny story. “She was like, ‘Babe, I got you that, it’s your gift,’” he says.

Later, Mr. Van Gogh logged onto Amazon, only to glimpse an Iron Man computer mouse his mother had purchased him as a gag Christmas gift in their shared order history. “I was like, ‘Oh, man, there are no surprises this year’,” he says.

Melissa Mok, a Bay Area, Calif.-based marketer, says the tidal flow of holiday packages has been so overwhelming, she had no choice but to start opening ahead of Christmas. If not, she says, they would have filled half the living room.

Some packages were gifts from clients or her work, others were routine household purchases. One contained a plush creature from the videogame Animal Crossing, an item she hadn’t ordered. It took a moment before she realized it was a Christmas present from a friend, one she hadn’t expected.

Ms. Mok, 39, says she liked being surprised that way, and that it was better than having to save the package under the tree.

“It was completely unexpected,” she says. “A moment of confusion, and then just a really joyous experience.”

Write to Te-Ping Chen at [email protected]