I want to get a second cat
Why do you want to get a second cat?
I am going to kill the first one
If you really don't want your first cat then you should drop him off at the animal shelter. Killing him would not only be illegal, but also make others think less of you.
You're making me mad, I'M JUST KIDDING.
Even if you are kidding then it is still kind of wrong. Many animals are abused each and every day and most people would say that's not something to joke about.