I fell down the stairs on purpose
Why would you fall down the stairs on purpose?
I wanted to see what would happen and everyone asked me if I got hurt.
You shouldn't be doing things that would hurt you on purpose. If you  feel the need to hurt yourself you should talk to a medical professional.
Everybody will know that I'm lying to the whole world. I just wanted to look cool. I don't think I'm a bad person.
It is better to be honest with people instead of trying to gain their sympathies. It is bad to harm yourself. You should want more for yourself and find better ways of getting the attention you seek.