They're also just naturally curious creatures. "Cats will knock objects over as a way to explore and engage with their environment," Adi Hovav, senior feline behavior counselor at the ASPCA Adoption Center, told The Dodo. "It is often a playful behavior, and in some cases cats learn this behavior gets them attention from their human friends."
Dr. Robert Proietto, a veterinarian in New York City, told The Dodo that "this behavior may be associated with hunting mice." But as with many cat mysteries, it's hard to be 100 percent certain. Dr. Proietto's firsthand experience leads him to think a playful hunting instinct might not be the only reason.
"It's mostly when I'm sleeping and my cat is ready to eat that everything is knocked off the counters to try and wake me," Proietto observed of his own feline companion.
"My cat, I believe, does it deliberately just to spite me," he said, which sums it all up pretty nicely.