I have facebook to keep track of these things.

@17th and P Streets! The two people were 30-something:

Guy: So when's your birthday?
Lady: Umm, well, it's in October.
Guy: Yeah? Nice, what date?
Lady: Late October?
Guy: I mean what day? Oh cool, is it on Halloween?
Lady: Uhh...I don't really...the 24th I guess.

It didn't seem like she didn't want to tell him, but that she was genuinely confused about her birthday.