Since Kyo was eight weeks old, her owners have been teaching her how to talk using cat speech buttons. Around 12 weeks old, Kyo began to use them more frequently, and displayed a particular affinity for certain foul-mouthed phrases, such as the "mad" button, which has since been swapped out for a perhaps more fitting "f*** you" button.
Have a look:
It is worth noting that Kyo most likely does not understand the gravity behind the phrase, especially if the button previously played back the word "mad." It is certainly entertaining, but perhaps an unfair way to characterize the sweet little guy.
The more likely reality is that Kyo simply associates the button with negative emotion, and does not intent at all to cuss out his humans.