China's Gen Z has embraced a new form of spiritual minimalism by gleefully hoarding what others might call trash.

From bubble tea cups and chopstick sleeves to concert tickets and train stubs, young people across the country are rewriting the rules of adulthood with a "grandma-core "philosophy: save everything, just in case.

They've embraced a new expression: "Questioning our moms, understanding our moms, becoming our moms." Once baffled by older generations' frugal lifestyles, today's young people are eager to collect life's leftovers.

Many say the habit kicks in like genetic programming around age 20 — a sudden realization that they've become just like their mothers, a frightening thought they resist but can't escape.

On social media platforms, young users proudly share how they have transformed "trash" into treasure. A takeout bag becomes a pencil case. A Luckin Coffee sleeve wraps a book. Thermal packaging from food deliveries is repurposed to carry lunch. And why buy storage boxes when sneakers come in perfectly good shoeboxes?

The current generation might splurge on luxury brands, but they're also the ones with drawers full of disposable chopsticks "for emergencies".

Underlying the behavior is a pragmatic philosophy. Save where you can, spend where you want. It's not about being cheap, they say, but rejecting wastefulness.

"Saving isn't about being stingy," said Luo Jiayi, a 20-year-old student at the Inner Mongolia University of Science & Technology. A milk tea enthusiast, Luo has amassed a collection of takeaway bags from his favorite drinks and meals.

Some bags are used as gift wrap, while others are turned into crafts or garbage bags. The rest, he said, are waiting for their moment.

"Many college students collect them," he said, adding that co-branded bags with popular films or video games often create a buzz on campus.

He admits storage is a challenge in his already cramped dorm.

"I'll bring some home during the May Day holiday for my mom to use," he said.

His schoolmate Lu Yunli, 19, shares the hobby, but for aesthetic reasons. An art major, she has been collecting attractive packaging since high school.

"I bring a pretty bag to class filled with delicious food, and it brightens my day," she said. "Who doesn't love beautiful things? And these bags are becoming more and more eye-pleasing."

Others collect more personal items. For Hu Dianhan, a 22-year-old student at the Changsha University of Science & Technology in Hunan province, it's movie stubs, concert tickets, handwritten notes and travel itineraries.

"These aren't receipts," she said. "They're irreplaceable time machines."

Hu keeps her memories in a scrapbook now thicker than a textbook — with tickets from her first solo movie, notes from her grandmother and concert stubs that, she said, "still smell like teenage dreams".

"Collecting is like gathering fragments of youth," she said. "It helps me stay connected to moments that matter."