The team behind Kickstarter-phenomenon Exploding Kittens promised to deliver a surprise in the box to backers. And so they did! When opened, the game box meows—yes, the sound of a cat.

The sound-producing packaging was provided by AdMagic, which has applied for a patent and is offering similar products through Other sound contraptions (e.g., musical greeting cards) typically trigger with the pull of a tab. AdMagic’s sound-boxes are triggered by exposure to light.