Stores often ask customers for a phone number at checkout, usually for rewards or digital receipts. If someone does not want to share it, they can normally just say no and finish paying.

But that choice can feel a little pointless if the store already has the information. One Walmart customer was caught off guard when she turned down a mobile receipt, only for the self-checkout machine to greet her by name moments later.

TikTok creator Maya (@maya_maybee) shared the experience in a video that has received more than 128,000 views. She claims she walked into Walmart without taking out her phone, grabbed a bottle of water, and headed to self-checkout. Nothing seemed unusual until it was time to get her receipt.

So how did it know?

At self-checkout, Maya was asked whether she wanted to enter her phone number for a mobile receipt. She declined. “I said, no. I clicked no,” she recalls before explaining that she paid and waited for a printed receipt.

Instead, the screen allegedly thanked her by name and said a receipt would be sent to a phone number ending in several digits. “I thought I told you, no, I don’t want one, I didn’t enter my phone number,” Maya says. “You just know who I am.”

The initial request was not unusual, since Walmart customers can choose a digital receipt at self-checkout. What remains unclear is how the checkout recognized Maya after she declined to enter her number.

One possibility raised by viewers was her payment method. Maya does not mention how she paid or whether she had previously saved the same card to a Walmart account.

Several commenters immediately pointed to her card. “They know your card,” one person commented, while another wrote, “The card you used to pay is linked to your Walmart account and that is how it knew who you are.” Someone else similarly suggested, “Card is likely linked to mobile receipts somewhere.”

That theory is possible if Maya had a card saved to a Walmart account. Walmart says an in-store purchase made with a payment card saved to a customer’s Walmart account can automatically appear in their online purchase history. The company also says store purchases can be linked when the name on the credit card matches the name on the Walmart account.

Walmart can also use payment details to find past receipts. Its receipt lookup service asks customers for the store location, purchase date, total, card type, and the last four digits of the card used.

That gives some context for why viewers pointed to Maya’s payment method. Walmart’s checkout technology, however, goes beyond simply processing a customer’s card.

Workers have previously shown what Walmart employees can see while customers scan their purchases, including handheld devices that show items being scanned at individual registers. That has given shoppers a closer look at how much monitoring can happen around self-checkout.

For some viewers, Maya’s experience raised a bigger question about customer privacy. “We need to normalize contacting our representatives voicing how illegal this feels & to get this changed,” one person wrote.

That concern is not entirely new. Walmart has faced scrutiny over how it handles information connected to certain purchases, though the company has said it works to protect customers’ personal information.

Whatever caused the checkout to recognize Maya, viewers clearly had plenty of theories. The bigger takeaway may be how little shoppers actually know about what information is already connected to them when they reach the register.