A tlak is a talk that isn't necessarily serious in nature, but is about deeper than normal-everyday conversations. Conversations starting off about life, relationships, opinions or ideals, religion, whatever and branching out from there are how good tlaks are done.
Tlaks can end up in less dirty versions of the Question Game
John: Dude, Jack, I need to have a tlak with you about something.
Jack: No problem man, just let me finish what I'm doing and I'll be right over.
Let's have a tlak over coffee sometime.