There are thousands of videos of cats purposely knock things off surfaces. But my cats have never done that. They've jostled a table when playing and caused some to fall. They've sprawled on a surface accidentally causing something to fall. Never have I seen them playfully send something crashing to the floor. With that said, they are the unusual exception. Muffin is normal, but she can definitely be taught not to do that and may, with maturity, lose interest in swatting things down. Don't give up hope, Randy!