A joke I liked

A woman is walking along the street and stops to give some money to a homeless man.  He thanks her and tells her that he appreciates her help.  "I wasn't always like this, you know."  The woman asks him what does he mean by that.  He says "I used to have millions of dollars in bank accounts all around the world."  The woman says "Oh my, what happened to you?"  He lowered his head and sadly replied "I forgot my mother's maiden name."