>To have friendly banter (playful and friendly exchange of teasing remarks) for hours on end
> A long and informal conversation with someone
> To gossip with friends at leisure
Chewing the fat is speculated to be something that was done at leisure by the North American Indians. Farmers in Britain would chew on pork fat when sitting idle or chatting with other farmers.
Another speculation is the fact that the phrase originates from the actual movement of the mouth when chewing fat which resembles when friends get together to gossip.
Example
The whole purpose for having this event is so that school friends can come together and chew the fat. That is why it is known as a reunion.
I was able to convince grandma to go with us – after chewing the fat for about an hour with her.