kickin' it ol' skool can imply many different things, but there are two main definitions:
1)Doing something like it was done in the '80s
2)(The most popularly used version): Hanging out with a good friend that you've grown up with.
Kaitlynn: Hey Tommy, what's poppin'?
Tommy: Ahhh, nothing...just kickin' it ol' skool with Jeremiah!