Confab implies a casual, relaxed conversation, not an official or serious discussion. After work, we had a nice confab over a cup of coffee.
Pro Tip 2/3
Private Setting
The word often suggests a conversation is private, perhaps with a sense of exclusivity. The two old friends had a confab about life in a quiet corner of the park.
Pro Tip 3/3
Brevity Implied
A confab is generally a brief, sometimes spontaneous, conversation, not a long dialogue. Can we have a quick confab about tomorrow's schedule?