I’m sitting in my favorite cafe, and a guy asks if he can plug in his cell phone.
He asks my first name. I tell him.
He asks my birthday. I tell him the month.
He asks the day. I asked why but for some reason told him.
He tells me he’s an artist, had been traveling and said I was the first person he’d met upon his return. Based on my birthday, he interpreted what his day would be like. (We ARE in California after all.)
He then asks my last name. I declined to tell him, stating that I’m in the witness protection program. I always find that line gets people to stop asking too-personal questions.
First name, last name, birthdate?
Be careful what you tell strangers. The search for much more personal information on you is only a web search away. 
Perhaps, you have something interesting to say?