I want to kill my friends roommates tarantula.
Why would you want to do that?
I don't like animals.
Killing someone's pet is mean. If you don't like the tarantula don't go to her home.
So it's okay to have a pet around if it is in their home? Also, I'm still going to hurt the tarantula.
Yes, people can have what pets they want as long as it is allowed by the laws in the place. You might be kicked out of their home if you kill their pets.