What does her lack of job/life have to do with this? It sounds like she needs help, if she wasn't joking around.

Think very loudly "You need to speak to a psychiatrist!"

Would it be less of an FML if she had a job or life?

"I hear you're not thinking about getting a job." That'll shut her up.

Well, can you?

Did she come downstairs....in your parents house that you both still live in?

"If I could hear your thoughts, I would have heard that you were thinking of coming downstairs and I would have gotten the fuck out of here!" Go full Inception on her!

Just tell her yes you can and that she doesn't think of very nice things so if she'd kindly stfu.

OP this really grim! How is it that you are living with a 35 year old mentally disturbed sister? Is she living with you or are both of you living with your parents? You really need to get out of there before things get worse. At the least someone needs to try to convince your sister to seek help.

My brother, a schizophrenic, had said the same thing to me before. Sounds like she needs help