As everyone who's ever ordered their supermarket shopping online knows, it's irritating when the product you want isn't in stock.
And to add insult to injury, sometimes you're given something completely random and weird to compensate for the fact that your toilet rolls aren't available.
See also: 10 mistakes we make at the supermarket
See also: The three habits of savvy supermarket shopping
Customers complain about this issue via social media on a daily basis as they're sent really disappointing shopping.
But one Tesco customer was left more confused than angry when he tried to add a pack of pantyliners into his weekly shop (presumably not for him) and was told he should instead buy... Yes, a Pedigree Dentaflex.
That's a bone especially designed to clean dog's teeth when they're eating it.
Nothing to do with pantyliners or feminine hygiene.
The shopper was told by Tesco to reinstall the app, but that still didn't fix the problem.
A spokesperson for Tesco said: "On the rare occasion that a customer's chosen product is unavailable, we like to suggest an alternative.
"We have corrected the error that led to this substitution being suggested."