(NEXSTAR) – Gearing up for your first cruise? Don’t be surprised if you find a few rubber duckies sometime between the breakfast buffet and bingo.

Over the past several years, it has become increasingly common for cruise passengers to hide rubber ducks throughout the ship for other guests to find. These “cruising ducks,” as they’re called, often come with tags containing instructions for the person who discovers them, who can keep the ducks for themselves or hide them for another passenger to find. (“Keep or hide, you decide!” many of the tags say.)

Guests are also encouraged to share photographs of the ducks they find on social media — specifically in online “Cruising Duck” Facebook groups boasting tens of thousands of members.

“Just got off the Carnival Vista,” one Facebook user wrote in a post shared to a cruising duck group. “We had so much fun!! Found 7 ducks!”

The origin of the trend can be traced back to Abby Davis, who was only 10 years old when she asked to bring a bag of rubber ducks on her first cruise in 2018, according to the largest “Cruising Ducks” Facebook group, of which there are more than 264,000 members.

“We got 50 ducks for a 7-day trip,” Abby’s mother Ashley Davis explained on CruisingDucks.com. After hiding a handful of the ducks each day, the pair soon noticed “people of all ages finding the ducks and having a good time looking for them,” Ashley Davis said.

There are, however, several rules for “cruise ducking.” For starters, guests are instructed to only hide ducks in public areas of the ship, but not in any shops, pools, hot tubs, spas, or near any emergency equipment. Passengers are also discouraged from putting ducks in precarious spots where they risk falling overboard, according to CruiseHive and The Points Guy.

But even with guidelines designed to keep the practice from becoming a nuisance, there are folks who would rather these ducks go the way of the dodo.

“Unpopular opinion, ducks are just additional trash that ppl leave around the ship. Like drink glasses and plates,” one traveler wrote on Reddit.

John Heald, the senior cruise director and brand ambassador for Carnival Cruise Line, also responded to a frustrated passenger who claimed to be boycotting Carnival until the ducks were banned.

“[It] makes me feel very sad, it really does,” Heald wrote, before instructing other followers to simply “hide them — find them — or ignore them.”

Those who participate, though, generally feel it’s nothing more than a harmless game intended to bring joy to fellow guests of all ages.

“Our grandchildren love to participate in this fun activity,” one Facebook user said. “And us ‘old’ folks enjoy it also.”