The growing craze for adult games of hide-and-seek at Ikea stores was sparked last summer when the Swedish retailer allowed popular Belgian blogger Elise De Rijck to hold an event at her local outlet at Wilrijk. Hide-and-seek enthusiasts were found hiding beneath beds, under blue Ikea shopping bags, and even inside unplugged fridges.

The concept is now proving popular in the Czech Republic and in Holland, where more than 19,000 people have signed up on Facebook to play hide-and-seek at a store in Amsterdam in April. Another 12,000 have signed up for an event in Utrecht.

But Ikea is worried that huge numbers of people cramming into stores could potentially cause a serious health and safety hazard.

“It’s hard to control. We need to make sure people are safe in our stores and that’s hard to do if we don’t even know where they are,” said Martina Smedberg, spokesperson for Ikea Netherlands, as reported by Bloomberg.

The original Belgian event was held after Elise wrote a bucket list of 30 things to do before her 30th birthday. “Initially, I created a Facebook event for my friends, but thousands of people started joining,” said Elise, quoted by ABC News. “Ikea contacted me and said they wanted to help me organise the event. They had to spend money hiring extra staff and security, but it brought them a lot of attention.”

Annelies Nauwelaerts, spokesperson for Ikea Belgium, confirmed to ABC that the Wilrijk event had been a big success. “We wanted to make her dream come true – and clearly the dream of thousands of others. But it was an exclusive, one-off thing.”

And that’s flat.