Kids are mad over them, schools might ban them, and adults are flogging them off online.
Supermarket chain Countdown's latest DreamWorks Heroes action cards are so highly sought-after that, despite the cards being handed out free with every $20 spent in store, a full set is being sold on Trade Me for about $200.
The promotion, which began on May 3, includes 42 collectible hologram cards featuring characters from children's movies The Croods, Kung Fu Panda, Puss in Boots, Shrek, Turbo and Madagascar. Stocks are expected to last until mid-June.
Principals' Federation president Phil Harding said the cards would be "like everything else, they too will pass".
"This sort of promotional material has been causing chaos for ages. They're just another thing the schools have to manage, and manage wisely."
He suggested schools use them as learning opportunities, or ban them completely.
Naenae Primary School principal Murray Bootten said the DreamWorks Heroes cards had not caused any problems so far.
However, previous card crazes had led to the school asking pupils to leave them at home, he said. "If this one carries on, it could become an issue."
Catherine Guyton, who was selling her cards online, had no idea why she began collecting. "Our kids are grown up and I don't even know why I bought the book," she said.
She later saw how popular the collectibles were, and that the book alone was going for about $50 on Trade Me. Adding the 115 cards she had collected, Guyton listed it starting at $30. It was up to $121 by the end of the week, with 967 views, 94 watchers, and 38 bids.
She was happy, "considering the outlay was $6 for the book, and you need to buy groceries anyway". She would add another bonus 10 cards to the winning bidder.
The money would go towards her 23-year-old son's trip to Florida for work experience.
Countdown's Wellington area manager, Andrew Cox, said there had been "a great response" to the cards. "We wanted to give our customers a fun play activity to enjoy with their kids."
Trading was so popular that the company organised swap meets at all its stores.
"We really want everyone to have fun sharing the cards and have an opportunity to complete their sets, but they have to remember that school comes first."
- The Dominion Post