Does shaving actually make hair grow back thicker/darker?
[mostly directed towards on face, but whatever]

No it just looks thicker at first because shaving gives the hair a blunt end I think anyway, but no it doesn't make it thicker/darker.

it doesn't O.o?

No, it doesn't. Like Nathan said, it looks thicker at first because of the blunt end.

Snopes, masters of urban myths and rumours:
http://www.snopes.com/oldwives/hairgrow.asp

Aw, I was going to post the Snopes link, but Ryan beat me to it.

Anyway, it doesn't grow back thicker.