Wake up, fill the boat with liquor and head out for the day. Not necessarily a group activity with other boats. It is not a social activity. Must be at least 2 people on the boat. Stop in the middle of the lake and get inebriated. A great way to spend a day.

Briefly, "the realization that each random passerby is living a life as vivid and complex as your own." Originally from the Dictionary of Obscure Sorrows, which has a lot more beautiful neologism definitions like this you might enjoy.