My grandmother did, and HE GAVE HER ONE!
She told God that if He did not prove to her that He exists, she would kill herself. This was when my mom was a girl. She recounted this story to me.
My mom saw something white walk past her room. Then there were screams (her mother's) coming from her parents' room. My grandpa was shouting, "calm down, Marge! It won't hurt you!"
The being stood at the foot of the bed, staring at my grandmother. It then turned and walked into the closet. It dissapeared.
Needless to say, my grandmother did not commit suicide.