Do you think I should tell people I am suicidal?
That sounds really serious, why would you tell people that you're suicidal?
I want to do it for the attention and sympathy.
Suicide is a very serious matter and you should only say that you're suicidal if it's true. Saying something like that if it's not true is hurtful to others that would spend time and effort trying to help you.
I don't understand what you're saying. I was just joking.
I know you didn't mean any harm, but suicide is serious and not something to make jokes about. It's very serious and should be treated like that.