An auntecdote can be any length of time, but a true auntecdote is a five mintue story stretched into an obscene amount of time.
Though sometimes long and drawn out, these stories are the stories you will continue to laugh at, and tell other people.
You: NO! What did she say this time?
Me: Apparently, her car broke down and was rescued by her high school sweetheart. Too bad it took us two days to hear the whole story.